LG Oven & Range Error Codes & Troubleshooting Guide
Find your LG oven or range error code and learn what it means, what may be causing it, and which components or systems may need attention. Explore common temperature sensor, heating, door lock, electrical, and control system fault codes with practical troubleshooting guidance.
BROWSE LG ERROR CODES BY APPLIANCE
LG REFRIGERATOR
ERROR CODES
Cooling, defrost, ice maker, sensor & communication fault codes
LG WASHER
ERROR CODES
Drain, spin, water supply, door lock & motor fault codes
LG DRYER
ERROR CODES
Heating, airflow, motor, sensor & control fault codes
LG OVEN & RANGE
ERROR CODES
Temperature, ignition, sensor, door lock & control fault codes
LG DISHWASHER
ERROR CODES
Drain, fill, heating, leak & circulation fault codes
On This Page
- How LG Oven & Range Error Codes Work
- What an LG Oven & Range Error Code Can Tell You
- An Error Code Does Not Always Mean a Part Has Failed
- Why LG Oven & Range Error Codes Can Vary by Model
- What to Do When an Error Code Appears
- Can You Clear an LG Oven & Range Error Code?
- When an Error Code Requires Professional Diagnosis
- Find Your LG Oven & Range Error Code
- CF1 — Left Front Induction Burner Temperature Sensor Error
- CF2 — Left Rear Induction Burner Temperature Sensor Error
- CF3 — Right Front Induction Burner Temperature Sensor Error
- CF4 — Right Rear Induction Burner Temperature Sensor Error
- CF5 — Left Inverter Board IGBT Error
- CF6 — Right Inverter Board IGBT Error
- CF7 — Communication Error Between Cooktop Main PCB & Left Inverter PCB
- CF8 — Communication Error Between Cooktop Main PCB & Right Inverter PCB
- CF9 — Flex Top Sensor Failure
- CFA — Over Current Error
- CFC — Over Voltage Error
- CFE — Blower Fan Error
- CFF — Box Fan Error
- F1 — Upper Oven Thermistor Error
- F10 — Upper Oven Door Locking System Failure
- F11 — Lower Oven Door Locking System Failure
- F16 — Lower Oven Too Hot
- F17 — Lower Convection Fan Error
- F18 — Lower Oven Meat Probe Error
- F19 — Lower Oven Temperature Sensor Error
- F2 — Lower Oven Temperature Sensor Error
- F20 — Lower Oven Door Locking System Failure
- F21 — Right Steam Sensor Open / Steam Sensor Failure
- F22 — Left Steam Sensor Open / Steam Sensor Failure
- F24 — Lower Oven Meat Probe Shorted Error
- F25 — Lower Oven Heating Error
- F27 — Cooling Fan Stalled or Locked During Self Clean
- F3 — Touch Pad Sensor Key Error
- F33 — Front Induction Burner Temperature Sensor Error
- F34 — Rear Induction Burner Temperature Sensor Error
- F36 — Inverter Board IGBT Error
- F38 — Communication Error Between Cooktop Main PCB & Inverter PCB
- F4 — Lower Oven Thermistor Error
- F42 — Over Voltage Error
- F45 — Box Fan Error
- F46 — IH (Induction Heater) Blow Fan Error
- F5 — Lower Oven Thermistor Error
- F51 — Griddle Sensor Open Error
- F52 — Griddle Sensor Shorted Error
- F56 — Griddle Is Too Hot Error
- F59 — Griddle Not Heating Error
- F6 — Upper Oven Too Hot
- F62 — Sous Vide Temperature Sensor Error
- F69 — Sous Vide Not Heating Error
- F7 — Upper Convection Fan Error
- F8 — Upper Oven Meat Probe Error
- F9 — No Heat Error (Upper Oven)
- HS — Hot Surface Indicator
- PF — Power Failure
- Sb — Sabbath Mode
Understanding LG Oven & Range Error Codes
Modern LG ovens and ranges use electronic control boards, temperature sensors, heating components, door switches, cooling fans, relays, and other electrical systems to monitor appliance operation.
When the control system detects an abnormal operating condition, it may display an error code on the control panel. Depending on the model, an LG oven or range error code may indicate a problem involving temperature sensing, heating, the oven door or locking system, electrical circuits, cooling fans, control boards, or communication between electronic components.
An error code can provide an important starting point for troubleshooting, but it should not automatically be interpreted as confirmation that a specific component has failed.
For example, a temperature-related error may be caused by a defective oven temperature sensor, but similar symptoms can also result from damaged wiring, a loose connector, an electrical connection problem, or an issue with the electronic control system.
Likewise, an oven that is not heating properly may have a problem with a heating element, igniter, power supply, wiring, relay, temperature sensor, or electronic control depending on the model and symptoms.
Understanding what the code represents can help narrow down the system that needs to be checked and avoid replacing parts unnecessarily.
How LG Oven & Range Error Codes Work
The main electronic control continuously receives information from sensors, switches, and other components throughout the oven or range.
Depending on the model, the control system may monitor:
- Oven cavity temperature
- Temperature sensor signals
- Bake and broil operation
- Gas ignition systems
- Electric heating elements
- Oven door position
- Door lock operation
- Cooling fan operation
- Power supply conditions
- Electrical circuits
- Control panel inputs
- Communication between electronic modules
When the control receives a signal outside the expected operating range—or does not receive an expected signal—it may store or display an error code.
For example, if the oven temperature sensor circuit becomes open or shorted, the control may detect an abnormal temperature signal. If the door locking system does not reach the expected position, a different fault code may appear.
Some codes can also be caused by wiring, connectors, power supply problems, or control-board issues rather than by the component named in the code description.
The exact meaning and diagnostic procedure can vary between LG models. Gas ranges and electric ranges use different heating systems, while newer models may include additional electronic controls, fans, sensors, or smart features.
For this reason, troubleshooting should begin with the exact error code shown on the display and the complete appliance model number.
What an LG Oven & Range Error Code Can Tell You
An LG oven or range error code is generated when the appliance’s electronic control system detects an operating condition outside the expected range.
The code can help identify which system or circuit should be investigated first, significantly narrowing the troubleshooting process.
Depending on the model and the specific code, the problem may involve:
- Oven temperature sensing
- Bake heating system
- Broil heating system
- Gas ignition system
- Electric heating elements
- Oven door switch
- Door locking mechanism
- Cooling or convection fan
- Electrical wiring
- Power supply
- Control panel
- Main control board
- Communication between electronic modules
For example, if the control receives an abnormal signal from the oven temperature sensor circuit, it may display a temperature-related error code.
However, this does not necessarily prove that the temperature sensor itself has failed.
The same abnormal signal could potentially be caused by:
- Damaged sensor wiring
- Loose electrical connector
- Open or shorted circuit
- Poor terminal contact
- Control-board problem
The same principle applies to heating, door lock, fan, and communication errors.
The Code Identifies a System, Not Always a Failed Part
An error code should usually be treated as a diagnostic direction rather than a final diagnosis.
For example:
Temperature sensor code
→ Check the sensor, resistance, wiring, connectors, and control circuit.
Door lock code
→ Check the door position, lock mechanism, switches, wiring, and control circuit.
Heating-related code
→ Check the appropriate gas or electric heating system, power supply, wiring, sensors, and controls.
This approach helps avoid replacing a component simply because its name appears in the error-code description.
Symptoms Matter Too
The error code becomes more useful when combined with the appliance’s actual symptoms.
Important questions include:
- Does the oven heat at all?
- Does it reach the selected temperature?
- Does the error appear during preheating?
- Does it occur only during Bake or Broil?
- Does the oven overheat?
- Does the door lock or unlock correctly?
- Does the code appear during or after Self Clean?
- Does the code appear immediately after power is restored?
- Is the problem intermittent?
The combination of the error code + symptoms + model number usually provides a much stronger starting point for diagnosis than the error code alone.
Key Point
An LG oven or range error code tells you where the control system detected an abnormal condition.
It does not always tell you which part needs to be replaced.
Use the code to identify the system that requires further testing.
An Error Code Does Not Always Mean a Part Has Failed
Seeing an error code on an LG oven or range does not automatically mean that a specific component has failed.
Modern appliances monitor electrical signals from sensors, switches, heating circuits, motors, and other components. The control board often knows that a signal is abnormal, but it may not be able to determine exactly why the signal is abnormal.
For example, suppose the control detects an incorrect oven temperature sensor signal.
Possible causes may include:
- Failed temperature sensor
- Open sensor circuit
- Shorted sensor circuit
- Damaged wiring
- Loose connector
- Corroded terminal
- Poor connection at the control board
- Control-board fault
Replacing the temperature sensor without checking the circuit may therefore fail to solve the problem.
Door Lock Errors Are Another Example
If an error code involves the oven door locking system, the lock motor or actuator is not automatically the failed component.
The problem could involve:
- Door not fully closed
- Misaligned door
- Damaged latch
- Lock motor or actuator
- Door or lock switch
- Wiring harness
- Loose connector
- Main control board
The control only knows whether it received the expected lock or unlock signal.
It cannot always determine which component prevented that signal from occurring.
Heating Errors Can Have Multiple Causes
Heating problems can be particularly complex because LG manufactures both gas and electric cooking appliances.
An electric oven may depend on:
- Bake element
- Broil element
- Temperature sensor
- Relays
- Wiring
- 120/240 V power supply
- Electronic control
A gas oven may instead depend on:
- Igniter
- Gas valve
- Temperature sensor
- Ignition circuitry
- Gas supply
- Wiring
- Electronic control
Two ovens with similar symptoms may therefore require completely different diagnostic procedures.
Temporary Conditions Can Also Produce Codes
Some errors can be related to temporary operating conditions, such as:
- Power interruption
- Voltage fluctuation
- Loose connection
- Temporary overheating
- Interrupted cooking cycle
- Control communication problem
If the code disappears after power is restored and never returns, a component may not require replacement.
If the same code repeatedly returns, however, the underlying circuit should be investigated.
Key Point
Do not use the error-code name as a replacement-parts list.
A better diagnostic approach is:
Identify the code → Understand the monitored system → Check simple causes → Inspect wiring/connections → Test the relevant components → Evaluate the control system if necessary
This can prevent unnecessary parts replacement and help identify the actual cause of the problem.
Why LG Oven & Range Error Codes Can Vary by Model
LG produces many different types of ovens and ranges, and they do not all use the same hardware or diagnostic systems.
Depending on the product line, an appliance may be:
- Gas
- Electric
- Dual fuel
- Freestanding
- Slide-in
- Single wall oven
- Double wall oven
- Convection-equipped
- Smart-connected
- Equipped with additional cooking or cleaning features
Because the internal systems differ, the exact meaning of an error code and the correct diagnostic procedure can also vary.
Gas and Electric Models Are Different
One of the most important distinctions is the heating system.
An electric oven may use:
- Electric bake element
- Broil element
- Heating relays
- 240 V heating circuits
A gas oven may use:
- Igniter
- Gas valve
- Gas burner
- Ignition circuitry
Therefore, a heating-related symptom should always be interpreted according to the appliance configuration.
Sensors and Wiring Can Also Vary
Even models using similar technology may have different:
- Sensor locations
- Connector layouts
- Wire colors
- Pin assignments
- Resistance specifications
- Voltage specifications
- Control boards
- Wiring diagrams
For this reason, technical values should not automatically be transferred from one LG model to another.
For example, if a diagnostic reference provides a specific resistance measurement between two connector pins, those pins should only be used when the information applies to the exact model or model family being serviced.
The Same Code May Have Different Diagnostic Paths
In some cases, the same displayed code may have different diagnostic information depending on:
- Model generation
- Gas vs. electric configuration
- Wall oven vs. range
- Control-board version
- Installed features
This is why our individual error-code sections identify model-specific differences whenever they are relevant.
Find the Complete Model Number
Before performing technical troubleshooting, locate the complete appliance model number.
Depending on the product, the model label may be found around areas such as:
- Oven door frame
- Storage drawer area
- Lower frame
- Side of the appliance frame
- Rating label
Use the model number to locate the correct technical documentation and wiring information.
Key Point
Do not assume that every LG oven or range displaying the same code uses exactly the same components or diagnostic procedure.
Always combine:
Error code + Complete model number + Appliance type + Symptoms
before making a repair decision.
What to Do When an Error Code Appears
When an error code appears on your LG oven or range, avoid immediately replacing parts.
Start by collecting information that can help determine why the control displayed the code.
Step 1 — Record the Exact Error Code
Write down the code exactly as it appears on the display.
If possible, take a photo before resetting or disconnecting the appliance.
Digital displays can make certain characters look similar, especially:
1andI0andO5andS8andB
Using the wrong code can lead to an entirely different troubleshooting path.
Step 2 — Record When the Code Appeared
The timing of the error can be diagnostically important.
Note whether it appeared:
- Immediately after turning the appliance on
- During preheating
- During Bake
- During Broil
- During convection cooking
- After reaching the selected temperature
- During Self Clean
- While the door was locking
- While the door was unlocking
- After a power interruption
- After the oven had been operating for a long time
For example, a code that appears only when the oven becomes hot may suggest a different condition from one that appears immediately after power-up.
Step 3 — Note the Symptoms
Record what the appliance is actually doing.
Examples include:
- Oven not heating
- Oven heating slowly
- Oven overheating
- Incorrect temperature
- Uneven cooking
- Bake not working
- Broil not working
- Door not locking
- Door remaining locked
- Cooling fan not operating normally
- Control panel behaving abnormally
The error code and symptoms should be evaluated together.
Step 4 — Check for a Recent Power Problem
Consider whether the code appeared after:
- Power outage
- Breaker trip
- Voltage interruption
- Electrical work
- Appliance installation
- Power cord replacement
- Moving the range
Some electronic errors can appear after an abnormal power event.
Step 5 — Perform Simple External Checks
Depending on the code, basic checks may include:
- Confirming that the oven door is fully closed
- Checking the circuit breaker
- Confirming that the appliance has power
- Allowing an overheated oven to cool
- Checking whether controls are responding normally
- Confirming that a gas appliance has an available gas supply
Do not disassemble the appliance unless you understand the electrical and gas hazards involved.
Step 6 — Find the Exact Code in This Guide
Use the error-code list below to identify the system associated with the displayed code.
Then follow the troubleshooting information for that specific code.
Key Point
Before resetting the appliance, collect:
Code → Model number → Symptoms → When the code appeared
These four pieces of information can make subsequent troubleshooting much more accurate.
Can You Clear an LG Oven & Range Error Code?
In some situations, an LG oven or range error code may disappear after the appliance is reset.
A reset can be useful when the code was caused by a temporary electronic condition or power interruption.
However, there is an important distinction between:
Clearing an error code
and
Repairing the problem that caused the error code.
They are not necessarily the same thing.
A Reset May Clear a Temporary Condition
If appropriate for the appliance, power can be disconnected and then restored after a short period.
This allows the electronic control system to restart.
If the code was caused by a temporary condition, it may not return.
A Reset Cannot Repair a Failed Circuit
Power cycling cannot repair:
- Open temperature sensor
- Shorted sensor
- Broken wiring
- Failed heating element
- Defective igniter
- Damaged door lock
- Failed switch
- Burned electrical connection
- Persistent control-board problem
If the control detects the same abnormal condition after restarting, the code will usually return.
Pay Attention to When the Code Returns
The timing can provide useful clues.
Returns immediately after power-up
→ A persistent electrical or sensor condition may still be present.
Returns during preheating
→ The problem may become detectable when the heating system operates.
Returns only at high temperature
→ A temperature-dependent component or connection may require investigation.
Returns during door locking or Self Clean
→ The locking or high-temperature system may be involved.
Do not assume that these patterns prove a specific component has failed, but they can help guide diagnosis.
Don’t Repeatedly Reset a Persistent Error
If the same error repeatedly returns, continuing to reset the appliance is unlikely to solve the underlying problem.
Repeated resets can also erase useful information about when the failure occurs.
Record the code and circumstances before resetting the appliance.
Key Point
A reset may clear a temporary electronic condition, but:
Code cleared ≠ Problem repaired
If the error repeatedly returns, diagnose the system identified by the code rather than continuing to reset the appliance.
When an Error Code Requires Professional Diagnosis
Some LG oven and range error codes can be investigated through basic external checks, but many require access to internal electrical or gas components.
Professional diagnosis is recommended when troubleshooting requires:
- Live voltage measurements
- Resistance measurements
- Internal wiring inspection
- Heating element testing
- Igniter testing
- Gas valve diagnosis
- Temperature sensor testing
- Door lock circuit testing
- Control-board measurements
- Relay diagnosis
- Connector pin testing
Electrical Ranges Can Use High Voltage
Many electric ranges and ovens use 120/240 V electrical systems.
Internal testing may expose energized terminals and circuits capable of causing serious electrical injury.
A circuit can also remain energized even when one heating function appears to be off.
Do not perform live-voltage testing unless you are qualified to work safely with appliance electrical systems.
Gas Ranges Require Additional Caution
Gas ovens introduce additional hazards involving:
- Natural gas or propane
- Gas valves
- Burners
- Ignition systems
- Combustion
- Gas connections
If you smell gas, do not continue troubleshooting the appliance or attempt repeated ignition cycles.
Follow appropriate gas-safety procedures and have the appliance or gas supply inspected by a qualified professional.
Overheating and Electrical Damage Need Attention
Stop using the appliance and arrange diagnosis if you notice conditions such as:
- Burning smell
- Smoke
- Sparking
- Melted wiring
- Burned terminals
- Repeated breaker trips
- Severe overheating
- Gas odor
- Abnormal electrical noise
These symptoms should not be treated as routine error-code troubleshooting.
When Professional Testing Is Most Useful
A technician may be needed when:
- The same error repeatedly returns.
- Basic checks do not identify the cause.
- A sensor requires resistance testing.
- Wiring continuity must be checked.
- Voltage needs to be measured.
- A gas ignition system requires diagnosis.
- The error points toward the control board.
- Multiple possible components could produce the same code.
Professional testing can determine whether the problem is actually the component named by the code or another part of the circuit.
Key Point
If diagnosis requires access to live electrical circuits, gas components, internal wiring, or electronic controls, professional service is the safer and more reliable approach.
Find Your LG Oven & Range Error Code
Use the list below to locate the exact code displayed on your LG oven or range.
Each error-code section is designed to explain:
- What the code means
- Which appliance system is involved
- Common possible causes
- What can be checked first
- Relevant model-specific differences
- When professional diagnosis may be necessary
Search by the Exact Displayed Code
Start with the characters shown on the appliance display.
For example, if your oven displays a code containing a letter followed by a number, use that exact combination rather than searching only for a general symptom such as “LG oven not heating.”
The exact code usually provides a more specific diagnostic starting point.
Confirm the Appliance Model
Before following technical measurements or replacing components, record the complete model number.
This is particularly important because LG error-code definitions and diagnostic procedures can differ between:
Gas Range → Electric Range → Wall Oven → Dual-Fuel Range → Different model generations
A resistance, voltage, connector, or wire-color specification should only be used when it applies to the relevant appliance configuration.
Use the Error Code Together With the Symptoms
Once you find your code, compare the explanation with what the oven or range is actually doing.
For example:
Error code + Oven not heating
may require investigation of the heating or temperature-control system.
Error code + Door won’t unlock
may direct diagnosis toward the locking system.
Error code + Incorrect temperature
may involve temperature sensing, wiring, heating control, or related circuits.
The code and symptoms together provide more useful information than either one alone.
Not Every Display Message Is an Error
Some LG display messages may represent:
- Operating status
- Control settings
- Special modes
- Maintenance information
- Smart appliance features
- Diagnostic or Test Mode information
When a displayed message is not an actual error, we will identify it clearly in the corresponding section.
This helps avoid unnecessary troubleshooting or component replacement.
Start With the Simple Checks
When you find your code, begin with the least invasive checks first.
A typical troubleshooting sequence is:
Confirm code → Confirm model → Check symptoms → Perform basic checks → Inspect relevant system → Perform electrical diagnosis if required
Do not jump directly to replacing the Main PCB or another expensive component unless testing supports that conclusion.
When the Code Keeps Returning
If the same code returns after basic troubleshooting or a reset, the appliance is likely continuing to detect the underlying abnormal condition.
At that point, further diagnosis may require:
- Sensor resistance testing
- Wiring continuity checks
- Voltage measurements
- Component testing
- Model-specific service information
Key Point
Find the exact LG oven or range error code below and use it as the starting point for troubleshooting.
For the most accurate diagnosis, always combine:
Exact Error Code + Complete Model Number + Appliance Type + Actual Symptoms
Then follow the corresponding code section to determine which system should be checked next.
CF1 — Left Front Induction Burner Temperature Sensor Error
The CF1 error code indicates a problem with the left front induction burner temperature sensor circuit.
On LG induction ranges and cooktops that use this diagnostic code, the control system monitors the temperature sensor associated with the left front induction cooking zone. If the expected sensor signal is missing or falls outside the expected range, the appliance may display the CF1 code.
The problem can involve the temperature sensor itself, its wiring or connector, or the voltage supplied by the cooktop control electronics.
What the CF1 Error Code Means
The left front induction burner uses a temperature sensor to provide temperature-related feedback to the cooktop control system.
If the control does not receive the expected signal from this sensor circuit, it may interpret the condition as a sensor fault and store or display CF1.
According to LG diagnostic information, CF1 can be caused by either:
- A defective induction temperature sensor
- Missing voltage from the cooktop control board
This means the code does not automatically confirm that the sensor itself has failed. The sensor circuit and control-board output should both be checked before parts are replaced.
Common Causes
Possible causes of an LG CF1 error include:
- Failed left front induction burner temperature sensor
- Open sensor circuit
- Shorted sensor circuit
- Loose sensor connector
- Damaged wiring between the sensor and control board
- Poor electrical connection
- Missing sensor supply voltage
- Cooktop System PCB problem
Because several electrical conditions can produce the same fault, replacing the sensor based only on the displayed code may not solve the problem.
What You Can Check
Start with basic inspection if the appliance can be safely accessed.
Check for:
- Loose or disconnected wiring
- Damaged sensor harness
- Burned or overheated connectors
- Corrosion at electrical terminals
- Visible damage around the left front induction cooking zone
If no obvious problem is found, the sensor circuit should be electrically tested.
Induction Temperature Sensor Resistance
LG specifies approximately:
57 kΩ at 77°F
for the induction temperature sensor associated with this diagnostic procedure.
The resistance measurement should be compared with the actual temperature of the sensor and with model-specific service information.
A reading that is open, shorted, or significantly outside the expected value may indicate a defective sensor or circuit problem.
Check Sensor Supply Voltage
LG also specifies checking for:
5 VDC from the Cooktop System PCB.
If the expected 5 VDC supply is missing, the problem may be related to:
- Cooktop System PCB
- Wiring between the PCB and sensor
- Connector or terminal problem
This distinction is important because installing a new sensor will not correct the error if the board is not supplying the required voltage.
Sensor vs. Control Board Diagnosis
A useful diagnostic sequence is:
CF1 displayed
→ Inspect sensor wiring and connectors
→ Check sensor resistance
→ Verify 5 VDC from Cooktop System PCB
→ Inspect circuit continuity
→ Evaluate the Cooktop System PCB if required
If the sensor measures correctly but the expected supply voltage is missing, diagnosis should move toward the wiring and control electronics rather than automatically replacing the sensor.
Can You Clear the CF1 Code?
A power reset may temporarily clear the display, but it will not repair a persistent sensor or control-circuit problem.
If CF1 returns after power is restored or when the left front induction zone is used, the control is likely continuing to detect the abnormal sensor condition.
Repeatedly resetting the appliance is therefore not a substitute for diagnosing the circuit.
When Professional Diagnosis Is Recommended
Professional service is recommended when troubleshooting requires:
- Opening the cooktop or range
- Resistance testing
- DC voltage measurements
- Wiring continuity checks
- Cooktop System PCB diagnosis
- Access to induction power electronics
Induction cooking appliances contain high-voltage electronic components, and internal testing should be performed only by someone qualified to work safely with these systems.
Key Point
CF1 indicates a left front induction burner temperature sensor circuit problem.
LG’s diagnostic procedure calls for checking:
- Induction temperature sensor: approximately 57 kΩ at 77°F
- Cooktop System PCB output: 5 VDC
The fault may be caused by the sensor, wiring, connectors, or the cooktop control board, so the code should be diagnosed before replacing components.
CF2 — Left Rear Induction Burner Temperature Sensor Error
The CF2 error code indicates a problem with the left rear induction burner temperature sensor circuit.
On LG induction ranges and cooktops that use this diagnostic code, the electronic control system monitors a temperature sensor associated with the left rear induction cooking zone. If the sensor circuit does not provide the expected signal, the control may display the CF2 error.
According to LG diagnostic information, the condition may be caused by a defective temperature sensor or by missing voltage from the main cooktop control system.
What the CF2 Error Code Means
The temperature sensor associated with the left rear induction burner provides temperature-related information to the cooktop electronics.
The control expects the sensor circuit to operate within a specific electrical range. If the signal is missing or abnormal, CF2 may be generated.
This does not automatically mean the temperature sensor itself needs to be replaced.
The problem may involve the sensor, wiring, electrical connections, or the voltage supplied by the Cooktop System PCB.
A proper diagnosis should therefore evaluate the entire sensor circuit rather than replacing the sensor based only on the displayed code.
Common Causes
Possible causes of the LG CF2 error include:
- Defective left rear induction burner temperature sensor
- Open temperature sensor circuit
- Shorted sensor circuit
- Loose or disconnected sensor connector
- Damaged wiring harness
- Poor electrical connection
- Missing sensor supply voltage
- Cooktop System PCB problem
The direct LG diagnostic information specifically identifies two primary areas to investigate: the sensor itself and voltage supplied from the main board.
What You Can Check
If the appliance can be safely inspected, begin with the sensor wiring and connections associated with the left rear induction cooking zone.
Look for:
- Loose connectors
- Partially disconnected plugs
- Damaged wiring
- Pinched or broken wires
- Burned or overheated terminals
- Poor connector contact
- Visible damage around the sensor circuit
If the wiring appears normal, electrical testing can help determine whether the problem is on the sensor side or control-board side of the circuit.
Check the Induction Temperature Sensor
LG specifies checking the induction temperature sensor for approximately:
57 kΩ at 77°F (25°C).
Resistance should be measured with the appliance disconnected from power and according to the appropriate service procedure.
Because temperature sensors change resistance with temperature, the actual sensor temperature should be considered when evaluating the measurement.
A sensor that reads open, shorted, or significantly outside the expected range may indicate a defective sensor or a problem in its circuit.
Check the Cooktop System PCB Voltage
LG also specifies checking for:
5 VDC from the Cooktop System PCB.
This measurement is important because CF2 can occur even when the temperature sensor itself is functional.
If the sensor resistance is within the expected range but the required voltage is missing, diagnosis should move toward:
- Wiring between the sensor and PCB
- Connector integrity
- PCB connections
- Cooktop System PCB
Replacing the temperature sensor would not correct a missing control-board voltage condition.
Sensor vs. Control Board Diagnosis
A logical diagnostic sequence for CF2 is:
CF2 displayed
→ Inspect left rear sensor wiring and connectors
→ Check sensor resistance
→ Verify 5 VDC from the Cooktop System PCB
→ Check circuit continuity and connections
→ Evaluate the Cooktop System PCB if necessary
This sequence helps separate a sensor problem from a wiring or electronic control problem.
For example, if the sensor measures approximately 57 kΩ at 77°F but the expected 5 VDC is absent, further investigation of the wiring and Cooktop System PCB is appropriate.
CF1 vs. CF2
CF1 and CF2 belong to the same general temperature-sensor fault family, but they identify different induction cooking zones.
CF1 → Left Front Induction Burner Temperature Sensor
CF2 → Left Rear Induction Burner Temperature Sensor
This distinction is important when diagnosing the appliance because testing should focus on the circuit associated with the cooking zone identified by the code.
Can You Clear the CF2 Code?
Disconnecting and restoring power may clear the displayed code if it resulted from a temporary electronic condition.
However, a reset cannot repair a failed sensor, damaged wiring, poor connection, or missing PCB voltage.
If CF2 returns after the appliance is restarted—particularly when the left rear induction burner is operated—the sensor circuit should be properly diagnosed.
Repeatedly resetting the appliance is not a substitute for identifying the underlying electrical problem.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended if troubleshooting requires:
- Opening the cooktop or range
- Accessing induction electronics
- Measuring temperature sensor resistance
- Measuring DC control voltage
- Checking wiring continuity
- Diagnosing the Cooktop System PCB
Induction appliances contain high-power electrical and electronic components. Internal voltage testing should only be performed by someone qualified to safely diagnose induction cooking equipment.
Key Point
CF2 indicates a problem with the left rear induction burner temperature sensor circuit.
LG’s diagnostic information calls for checking:
Temperature sensor: approximately 57 kΩ at 77°F (25°C)
Cooktop System PCB: approximately 5 VDC
The sensor itself may be defective, but wiring, connectors, missing supply voltage, or the Cooktop System PCB can also be responsible for the CF2 error.
CF3 — Right Front Induction Burner Temperature Sensor Error
The CF3 error code indicates a problem with the right front induction burner temperature sensor circuit.
On LG induction ranges that use this diagnostic code, the cooktop control system monitors a temperature sensor associated with the right front induction cooking zone. If the control does not receive the expected signal from this sensor circuit, it may display CF3.
According to LG diagnostic information, the condition can be caused by a defective sensor or by missing voltage from the main control system.
What the CF3 Error Code Means
The right front induction cooking zone uses a temperature sensor to provide temperature-related feedback to the cooktop electronics.
The Cooktop System PCB monitors this sensor circuit while the appliance operates. If the sensor signal is missing or outside the expected electrical range, the control can identify the condition as a right front induction burner temperature sensor error.
Importantly, CF3 does not automatically confirm that the temperature sensor itself has failed.
The fault may involve:
- The induction temperature sensor
- Sensor wiring
- Electrical connectors
- Sensor circuit connections
- Voltage supplied by the Cooktop System PCB
The entire circuit should therefore be evaluated before replacing components.
Common Causes
Possible causes of an LG CF3 error include:
- Defective right front induction burner temperature sensor
- Open temperature sensor circuit
- Shorted sensor circuit
- Loose or disconnected sensor connector
- Damaged wiring
- Poor electrical connection
- Missing sensor supply voltage
- Cooktop System PCB problem
LG’s diagnostic information specifically identifies a bad sensor or missing voltage from the main board as the cause of CF3.
What You Can Check
If the appliance can be safely accessed, begin by inspecting the wiring and connectors associated with the right front induction cooking zone.
Look for:
- Loose electrical connectors
- Partially disconnected plugs
- Damaged or pinched wiring
- Broken wires
- Burned or overheated terminals
- Poor connector contact
- Visible damage around the sensor circuit
A loose connection can interrupt the sensor signal even when the temperature sensor itself is still functional.
If no visible problem is found, electrical testing is needed to distinguish between a sensor problem and a control-side problem.
Check the Induction Temperature Sensor
LG specifies checking the induction temperature sensor for approximately:
57 kΩ at 77°F (25°C).
Because this is a temperature-sensitive component, resistance should be evaluated in relation to the actual temperature of the sensor.
A sensor reading that is open, shorted, or substantially outside the expected range may indicate a defective sensor or a problem in the sensor circuit.
The measurement should be performed with the appliance safely disconnected from power and according to the appropriate model-specific service procedure.
Check the Cooktop System PCB Voltage
LG also specifies checking for:
5 VDC from the Cooktop System PCB.
This is an important part of the CF3 diagnostic process.
If the sensor itself measures correctly but the required voltage is missing, the problem may be located elsewhere in the circuit.
Areas to investigate include:
- Wiring between the sensor and Cooktop System PCB
- Connector terminals
- Harness connections
- Cooktop System PCB
Replacing the temperature sensor would not correct CF3 if the sensor is not receiving the required voltage from the control system.
Sensor vs. Cooktop System PCB Diagnosis
A logical diagnostic sequence for CF3 is:
CF3 displayed
→ Inspect right front sensor wiring and connectors
→ Check induction temperature sensor resistance
→ Verify 5 VDC from the Cooktop System PCB
→ Check circuit connections and wiring
→ Evaluate the Cooktop System PCB if necessary
This sequence helps avoid replacing the temperature sensor before determining whether the control system is providing the required voltage.
If the sensor measures approximately 57 kΩ at 77°F but the expected 5 VDC is missing, further diagnosis should focus on the wiring, connections, and Cooktop System PCB.
CF1 vs. CF2 vs. CF3
These codes belong to the same general induction temperature-sensor fault family, but each code identifies a different cooking zone:
CF1 → Left Front Induction Burner Temperature Sensor
CF2 → Left Rear Induction Burner Temperature Sensor
CF3 → Right Front Induction Burner Temperature Sensor
The distinction matters because troubleshooting should focus on the sensor circuit associated with the specific cooking zone identified by the code.
Can You Clear the CF3 Code?
Disconnecting and restoring power may temporarily clear CF3 if the code resulted from a temporary electronic condition.
However, a reset cannot repair:
- A defective temperature sensor
- Open or shorted wiring
- Loose electrical connection
- Missing control voltage
- Cooktop System PCB problem
If CF3 returns—particularly when the right front induction cooking zone is operated—the sensor circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when troubleshooting CF3 requires:
- Opening the range or cooktop
- Accessing induction electronics
- Measuring sensor resistance
- Measuring DC control voltage
- Testing wiring continuity
- Diagnosing the Cooktop System PCB
Induction cooking systems contain high-power electronic components. Internal electrical testing should only be performed by someone qualified to safely diagnose induction appliances.
Key Point
CF3 indicates a problem with the right front induction burner temperature sensor circuit.
LG’s diagnostic procedure specifies checking:
Induction Temperature Sensor: approximately 57 kΩ at 77°F (25°C)
Cooktop System PCB: 5 VDC
The sensor may be defective, but wiring, connectors, missing control voltage, or the Cooktop System PCB can also cause CF3. The sensor circuit should be tested before replacing components.
CF4 — Right Rear Induction Burner Temperature Sensor Error
The CF4 error code indicates a problem with the right rear induction burner temperature sensor circuit.
On LG induction ranges that use this diagnostic code, the cooktop electronic control system monitors a temperature sensor associated with the right rear induction cooking zone. If the control does not receive the expected signal from this sensor circuit, the appliance may display CF4.
The fault can be caused by the temperature sensor itself or by a problem with the voltage supplied by the cooktop control electronics.
What the CF4 Error Code Means
The right rear induction cooking zone uses a temperature sensor to provide temperature-related feedback to the electronic control system.
During operation, the Cooktop System PCB expects the sensor circuit to produce an electrical signal within the appropriate range. If the signal is missing or abnormal, the control can identify the condition as a right rear induction burner temperature sensor error.
LG specifically identifies CF4 as:
Right Rear Induction Burner Temperature Sensor Error.
This does not automatically mean the temperature sensor needs to be replaced.
The problem may be located anywhere within the monitored circuit, including the sensor, its connections, wiring, or the voltage supplied by the Cooktop System PCB.
Common Causes
Possible causes of an LG CF4 error include:
- Defective right rear induction burner temperature sensor
- Open temperature sensor circuit
- Shorted sensor circuit
- Loose or disconnected electrical connector
- Damaged sensor wiring
- Poor terminal contact
- Missing sensor supply voltage
- Cooktop System PCB problem
LG’s diagnostic information specifically identifies a bad sensor or missing voltage from the main board as the underlying condition to investigate.
What You Can Check
Begin with a visual inspection of the right rear induction burner sensor circuit if the appliance can be safely accessed.
Look for:
- Loose connectors
- Disconnected plugs
- Damaged or pinched wiring
- Broken conductors
- Burned or overheated terminals
- Poor connector contact
- Visible damage around the sensor connections
A wiring or connection problem can interrupt the temperature sensor signal even when the sensor itself is operating normally.
If no obvious damage is found, electrical testing is required to determine whether the problem is associated with the sensor or the cooktop control system.
Check the Induction Temperature Sensor
LG specifies checking the induction temperature sensor for approximately:
57 kΩ at 77°F (25°C).
Because the component is a temperature sensor, its resistance changes with temperature. The measurement should therefore be evaluated with the actual sensor temperature in mind.
If the sensor is approximately 77°F but its resistance is significantly different from the specified value—or the circuit reads completely open or shorted—the sensor or its circuit should be investigated further.
Resistance testing should be performed with power disconnected and according to the appropriate service procedure for the appliance.
Check the Cooktop System PCB Voltage
LG’s CF4 diagnostic procedure also specifies checking for:
5 VDC from the Cooktop System PCB.
This check helps determine whether the control electronics are providing the expected voltage to the temperature sensor circuit.
If the sensor resistance is within the expected range but the required voltage is missing, possible areas to investigate include:
- Sensor wiring harness
- Connector terminals
- Connections at the Cooktop System PCB
- Cooktop System PCB itself
This is why replacing the temperature sensor based only on CF4 can result in an unnecessary repair.
Sensor vs. Cooktop System PCB Diagnosis
A logical diagnostic sequence for CF4 is:
CF4 displayed
→ Inspect the right rear sensor wiring and connectors
→ Measure the induction temperature sensor resistance
→ Verify 5 VDC from the Cooktop System PCB
→ Check wiring and circuit continuity
→ Evaluate the Cooktop System PCB if necessary
This separates two important possibilities identified by the LG diagnostic information:
Sensor problem
The sensor does not provide the expected electrical characteristics.
Control-side problem
The sensor may be functional, but the expected voltage from the Cooktop System PCB is missing.
For example, if the sensor measures approximately 57 kΩ at 77°F but there is no expected 5 VDC supply, diagnosis should continue toward the wiring, connections, and Cooktop System PCB.
CF1 vs. CF2 vs. CF3 vs. CF4
The first four CF codes form a clear group of induction burner temperature sensor faults:
CF1 → Left Front Induction Burner Temperature Sensor
CF2 → Left Rear Induction Burner Temperature Sensor
CF3 → Right Front Induction Burner Temperature Sensor
CF4 → Right Rear Induction Burner Temperature Sensor
Although these codes involve the same general type of sensor circuit, each identifies a different induction cooking zone.
This distinction is important because diagnosis should focus on the wiring, sensor, and electronic circuit associated with the specific burner identified by the displayed code.
Can You Clear the CF4 Code?
Disconnecting and restoring power may clear CF4 if it was caused by a temporary electronic condition.
However, resetting the appliance cannot repair a persistent problem such as:
- Failed temperature sensor
- Open or shorted circuit
- Damaged wiring
- Loose connector
- Missing PCB voltage
- Cooktop System PCB fault
If CF4 returns after power is restored, particularly when the right rear induction cooking zone is operated, the sensor circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when CF4 troubleshooting requires:
- Opening the range or cooktop
- Accessing induction electronics
- Measuring sensor resistance
- Measuring DC control voltage
- Checking wiring continuity
- Testing PCB connections
- Diagnosing the Cooktop System PCB
Induction cooking appliances contain high-power electronic circuits. Internal electrical testing should only be performed by someone qualified to safely work with induction appliance systems.
Key Point
CF4 indicates a problem with the right rear induction burner temperature sensor circuit.
LG specifies two primary diagnostic checks:
Induction Temperature Sensor: approximately 57 kΩ at 77°F (25°C)
Cooktop System PCB: 5 VDC
The error may be caused by the sensor itself or by a problem with the sensor circuit or voltage supplied by the cooktop control system. Testing the circuit before replacing components helps avoid unnecessary parts replacement.
CF5 — Left Inverter Board IGBT Error
The CF5 error code indicates a problem with the IGBT (Insulated Gate Bipolar Transistor) on the left inverter board of an LG induction range or cooktop.
Unlike CF1 through CF4, which identify temperature sensor circuit problems associated with individual induction cooking zones, CF5 points to the power electronics responsible for controlling the induction system.
According to LG diagnostic information, CF5 means that the IGBT located on the left inverter board is defective. LG identifies the prescribed solution as replacement of the inverter board.
What the CF5 Error Code Means
Induction cooking does not heat the cookware with a conventional electric heating element.
Instead, the appliance uses inverter electronics to control high-frequency electrical power supplied to the induction system. An important component within this power-control circuitry is the IGBT — Insulated Gate Bipolar Transistor.
The IGBT acts as a high-power electronic switching device. It allows the inverter electronics to rapidly control electrical current used by the induction cooking system.
When the appliance detects a failure associated with the IGBT on the left inverter board, it may display CF5.
LG specifically identifies CF5 as the:
Left Inverter Board Error
with the defective IGBT located on the inverter board.
What Is an IGBT?
IGBT stands for:
Insulated Gate Bipolar Transistor
It is a semiconductor device commonly used in high-power electronic systems where electrical current must be switched quickly and efficiently.
In an induction cooking appliance, inverter circuitry uses power semiconductors to control the energy required to generate the electromagnetic field that heats compatible cookware.
Because an IGBT operates within the high-power section of the induction system, a failure can prevent the affected inverter circuitry from operating correctly.
CF5 therefore represents a fundamentally different type of problem from a simple temperature-sensor fault.
Common Cause
LG’s diagnostic information is unusually direct for this code.
The listed cause is:
The IGBT is defective.
The IGBT is located on the left inverter board.
Unlike some other error codes where LG provides several possible sensor, wiring, or voltage checks, the CF5 documentation identifies the inverter-board IGBT itself as the failed component.
Symptoms That May Accompany CF5
Because CF5 involves the left inverter board, the induction cooking system associated with that electronics section may not operate normally.
Depending on the exact appliance configuration and model, the user may notice symptoms such as:
- CF5 appearing on the display
- One or more induction cooking zones not operating
- Cooking zones shutting down
- Failure to begin normal induction heating
- Error returning after the appliance is restarted
The exact cooking zones controlled by a particular inverter board can vary by appliance design, so the complete model number and model-specific service information should be used when determining which parts of the cooktop are associated with the left inverter board.
What You Can Check
CF5 is not primarily a user-serviceable error.
Before internal diagnosis, basic external checks can include:
- Record the exact CF5 code.
- Note which induction cooking zones were operating when the error appeared.
- Check whether the error appeared immediately or after the cooktop had been operating.
- Record the complete appliance model number.
- Check whether the error returns after the appliance is restarted.
If CF5 repeatedly returns, further troubleshooting requires access to the induction power electronics.
Left Inverter Board Diagnosis
LG identifies the defective IGBT as being located on the Inverter Board and identifies CF5 specifically as the Left Inverter Board Error.
This distinction is important because an induction range may contain multiple electronic assemblies responsible for controlling different portions of the cooking system.
The diagnostic focus for CF5 should therefore be the left inverter board, rather than the individual burner temperature sensor circuits associated with CF1–CF4.
Inverter Board Replacement
For CF5, LG’s specified solution is:
Replace Inverter Board.
This is an important difference from many sensor-related codes.
LG’s CF5 diagnostic information does not provide a sensor resistance value, 5 VDC sensor-supply check, or a separate component replacement procedure. Instead, the fault is identified at the inverter-board level.
For this reason, the inverter board should be identified using the complete appliance model number before replacement.
CF1–CF4 vs. CF5
CF5 marks an important change in the CF error-code series.
CF1 → Left Front Induction Burner Temperature Sensor Error
CF2 → Left Rear Induction Burner Temperature Sensor Error
CF3 → Right Front Induction Burner Temperature Sensor Error
CF4 → Right Rear Induction Burner Temperature Sensor Error
CF5 → Left Inverter Board IGBT Error
CF1 through CF4 direct diagnosis toward individual temperature sensor circuits.
CF5 instead directs diagnosis toward the power electronics on the left inverter board.
This is why the diagnostic procedure used for CF1–CF4 should not simply be applied to CF5.
Can You Clear the CF5 Code?
Disconnecting and restoring power may restart the electronic controls and temporarily remove the code from the display.
However, LG identifies CF5 as a defective IGBT condition on the left inverter board. A power reset cannot repair a failed semiconductor component.
If CF5 returns after power is restored, repeatedly resetting the appliance is unlikely to correct the underlying problem.
The inverter system should be professionally diagnosed.
When Professional Diagnosis Is Recommended
CF5 should generally be treated as a professional repair issue.
The inverter board is part of the induction appliance’s high-power electronic system. Accessing or testing this circuitry can expose a technician to hazardous electrical energy.
Professional diagnosis is appropriate when:
- CF5 repeatedly returns
- One or more induction zones stop operating
- The appliance shuts down during induction operation
- The inverter electronics require inspection
- The left inverter board requires replacement
The appliance should be disconnected from power before internal service, and appropriate electrical safety procedures should be followed.
Key Point
CF5 indicates a defective IGBT on the left inverter board.
LG identifies:
Error: Left Inverter Board IGBT Error
Cause: Defective IGBT located on the inverter board
CF5 designation: Left Inverter Board Error
Solution: Replace the inverter board.
Unlike CF1–CF4, CF5 is not an individual induction burner temperature sensor error. It indicates a fault within the induction power electronics and generally requires inverter-board-level repair.
CF6 — Right Inverter Board IGBT Error
The CF6 error code indicates a failure involving the IGBT (Insulated Gate Bipolar Transistor) on the right inverter board of an LG induction range or cooktop.
The inverter board is part of the high-power electronic system responsible for controlling induction heating. When the appliance detects a problem with the IGBT on the right-side inverter electronics, it may display the CF6 error code.
According to LG diagnostic information, CF6 specifically identifies the Right Inverter Board Error, and the prescribed solution is replacement of the inverter board.
What the CF6 Error Code Means
Induction cooking systems use sophisticated power electronics rather than conventional exposed heating elements.
The inverter electronics control the electrical energy used to generate the electromagnetic field that heats compatible cookware. One of the critical electronic components responsible for switching this power is the IGBT — Insulated Gate Bipolar Transistor.
When the IGBT associated with the right inverter board becomes defective, the induction control system may no longer be able to regulate the affected power circuit correctly.
The appliance can detect this abnormal condition and display CF6.
LG identifies the code as:
Right Inverter Board IGBT (Insulated Gate Bipolar Transistor) Error.
What Is an IGBT?
An Insulated Gate Bipolar Transistor (IGBT) is a high-power semiconductor switching device.
In an induction cooking system, power electronics must switch electrical current rapidly and precisely to create the electromagnetic energy used for heating cookware.
The IGBT performs an important role in this process.
Unlike a temperature sensor, switch, or simple mechanical component, the IGBT is integrated into the inverter electronics. A failure in this component is therefore considered an inverter-board-level fault.
This is why CF6 requires a very different diagnostic approach from the CF1–CF4 temperature sensor errors.
Common Cause
LG’s diagnostic information provides a specific cause for CF6:
The IGBT is defective.
The source also states that the IGBT is located on the Inverter Board and that CF6 identifies the Right Inverter Board Error.
Therefore, the primary diagnostic focus is not an individual burner temperature sensor or its 5 VDC circuit, but the right-side inverter power electronics.
Symptoms That May Accompany CF6
Because the fault involves the right inverter board, the appliance may have difficulty operating the induction cooking zones controlled by that electronics section.
Depending on the specific LG model and cooktop configuration, possible symptoms may include:
- CF6 appearing on the display
- One or more induction cooking zones failing to heat
- Affected cooking zones shutting down
- Induction heating stopping unexpectedly
- The code returning after the appliance is restarted
The exact cooking zones controlled by the right inverter board can vary by model. For that reason, the complete model number and model-specific wiring information should be used when determining which induction zones are associated with the board.
What You Can Check
CF6 is primarily an internal electronic fault rather than a simple user-correctable condition.
Before internal service, useful observations include:
- Record the exact CF6 code.
- Note which cooking zones were operating when CF6 appeared.
- Determine whether the code appears immediately or only after heating begins.
- Record the complete model number.
- Note whether the code returns after the appliance is restarted.
If CF6 consistently returns, diagnosis should focus on the right inverter electronics.
Internal inspection or electrical testing should not be attempted unless the person performing the work is qualified to service induction power electronics.
Right Inverter Board Diagnosis
LG specifically identifies CF6 as the:
Right Inverter Board Error.
This is an important distinction because an induction cooking appliance can use separate electronic sections to control different cooking zones.
The diagnostic focus for CF6 should therefore be the right inverter board and its associated power electronics.
This differs from CF1–CF4, where troubleshooting focuses primarily on individual induction burner temperature sensor circuits.
Inverter Board Replacement
LG’s specified solution for CF6 is:
Replace Inverter Board.
The source does not provide a separate resistance or voltage specification for diagnosing the IGBT itself on this page.
For this reason, we should not apply the 57 kΩ sensor resistance or 5 VDC sensor-circuit test used for CF1–CF4 to CF6.
Those measurements apply to a different type of fault.
The correct inverter board should always be identified using the complete appliance model number before replacement.
CF5 vs. CF6
CF5 and CF6 form a pair of inverter-board IGBT errors:
CF5 → Left Inverter Board IGBT Error
CF6 → Right Inverter Board IGBT Error
Both codes involve a defective IGBT located on an inverter board, but they identify different sides of the induction power-control system.
This distinction helps determine which inverter board requires attention.
The earlier CF codes belong to a different diagnostic group:
CF1 → Left Front Induction Burner Temperature Sensor
CF2 → Left Rear Induction Burner Temperature Sensor
CF3 → Right Front Induction Burner Temperature Sensor
CF4 → Right Rear Induction Burner Temperature Sensor
CF5 → Left Inverter Board IGBT Error
CF6 → Right Inverter Board IGBT Error
Can You Clear the CF6 Code?
Disconnecting power may restart the electronic control system and temporarily remove CF6 from the display.
However, LG identifies the underlying condition as a defective IGBT on the right inverter board.
A power reset cannot repair a failed semiconductor component.
If CF6 returns after power is restored, especially when the induction cooking system begins operating, repeatedly resetting the appliance is unlikely to solve the problem.
The inverter electronics require further diagnosis and repair.
When Professional Diagnosis Is Recommended
CF6 generally requires professional appliance service because the fault is located within the induction power electronics.
Professional diagnosis is appropriate when:
- CF6 repeatedly returns
- One or more induction zones stop heating
- The cooktop shuts down during operation
- The right inverter board requires inspection
- Inverter electronics require electrical testing
- The inverter board requires replacement
Induction appliances contain high-power electronics and can retain hazardous electrical energy. Internal diagnosis should only be performed using appropriate electrical safety procedures by someone qualified to service induction systems.
Key Point
CF6 indicates a defective IGBT associated with the right inverter board.
LG identifies:
Error: Right Inverter Board IGBT Error
Cause: Defective IGBT
Location: Inverter Board
CF6 designation: Right Inverter Board Error
Solution: Replace the inverter board.
CF6 is therefore an inverter power-electronics fault, not an individual burner temperature sensor error.
CF7 — Communication Error Between Cooktop Main PCB & Left Inverter PCB
The CF7 error code indicates a communication problem between the Cooktop Main PCB and the Left Inverter PCB in an LG induction range or cooktop.
These electronic control boards must communicate with each other for the induction cooking system to operate correctly. If communication between the main cooktop control and the left inverter electronics is interrupted or becomes unreliable, the appliance may display CF7.
According to LG diagnostic information, the primary causes are a loose connection at a connector or a PCB failure.
What the CF7 Error Code Means
An LG induction cooking system uses multiple electronic control assemblies.
The Cooktop Main PCB manages and coordinates cooktop operation, while the inverter electronics control the high-power induction circuits used to operate the cooking zones.
For proper operation, these boards must exchange electronic signals.
CF7 appears when the expected communication between the:
Cooktop Main PCB ↔ Left Inverter PCB
is not functioning correctly.
This is therefore different from an individual burner temperature sensor error or an IGBT error.
CF7 specifically directs diagnosis toward the communication path between two electronic boards.
Common Causes
LG identifies two primary causes for CF7:
- Loose connection at a connector
- PCB failure
In practical diagnosis, this means attention should be focused on the harness and connections between the Cooktop Main PCB and Left Inverter PCB before assuming that an electronic board must be replaced.
Areas requiring inspection may include:
- Wiring harness between the boards
- Loose electrical connectors
- Partially seated connectors
- Damaged connector terminals
- Broken or damaged wiring
- Poor electrical contact
- Cooktop Main PCB
- Left Inverter PCB
Because a connection problem can interrupt communication, CF7 does not automatically prove that one of the PCBs has failed.
3-Blink Burner LED Indicator
LG provides another useful diagnostic clue for CF7.
According to the source:
The burner may show a 3-blink code on the burner LED indicator.
This additional indication may help confirm that the problem is associated with the communication fault identified by CF7.
However, the exact display behavior can depend on the appliance configuration, so the complete model number should still be considered during diagnosis.
What You Can Check
If CF7 appears, begin by recording:
- The exact CF7 code
- Which cooking zones were being used
- Whether any burner LED is blinking
- Whether the code appeared immediately or during cooking
- Whether the affected cooking zones still operate
- The complete appliance model number
If internal inspection is performed by a qualified technician, the communication harness and connectors between the Cooktop Main PCB and Left Inverter PCB should be checked.
Look for:
- Loose connectors
- Connectors that are not fully seated
- Damaged wiring
- Broken conductors
- Bent or damaged connector terminals
- Burned or overheated connections
- Signs of damage on either PCB
A poor harness connection should be corrected before replacing an electronic control board.
Check the Harness Connections
LG’s specified solution begins with:
Check for poor connection of harness.
This makes the wiring connection an important first diagnostic step.
Disconnecting and reconnecting a harness may reveal:
- Connector not fully seated
- Loose terminal
- Damaged terminal
- Broken wire
- Poor contact between connector and PCB
The wiring path should also be inspected for physical damage.
If the harness and connectors are secure and electrically intact but CF7 continues to return, diagnosis can proceed toward the electronic boards.
Cooktop Main PCB vs. Left Inverter PCB
Because CF7 represents communication between two boards, identifying the failed side may require further diagnosis.
The communication path can be represented as:
Cooktop Main PCB → Harness / Connectors → Left Inverter PCB
A failure anywhere along this path can prevent normal communication.
For this reason, replacing the Left Inverter PCB simply because CF7 mentions it would not necessarily be the correct first step.
Likewise, the Cooktop Main PCB should not automatically be replaced without first checking the communication connections.
LG’s source summarizes the repair direction as:
Check for poor connection of harness or replace PCB.
CF5 vs. CF7
CF5 and CF7 both involve the left-side inverter system, but they identify very different problems.
CF5 — Left Inverter Board IGBT Error
The fault involves the IGBT power electronics on the left inverter board.
CF7 — Cooktop Main PCB / Left Inverter PCB Communication Error
The fault involves communication between the two electronic boards.
This distinction matters because CF5 directs diagnosis toward an inverter-board component failure, while CF7 first requires attention to the communication harness, connectors, and PCBs.
CF7 Diagnostic Sequence
A practical diagnostic sequence based on LG’s information is:
CF7 displayed
→ Check for 3-blink burner LED indication
→ Inspect communication harness
→ Check connectors at Cooktop Main PCB
→ Check connectors at Left Inverter PCB
→ Inspect wiring and terminals for damage
→ Correct any poor connection
→ If communication fault remains, diagnose the PCBs
→ Replace the failed PCB if confirmed
This approach helps avoid replacing an expensive control board when the actual cause is a poor electrical connection.
Can You Clear the CF7 Code?
Disconnecting power and restarting the appliance may temporarily clear CF7 if communication was interrupted by a transient electronic condition.
However, a reset cannot repair:
- Loose connector
- Damaged harness
- Broken wire
- Poor terminal contact
- Failed Cooktop Main PCB
- Failed Left Inverter PCB
If CF7 returns, especially when the induction system begins operating, the communication circuit should be inspected.
Repeatedly resetting the range without correcting the communication problem is unlikely to provide a permanent solution.
When Professional Diagnosis Is Recommended
CF7 generally requires professional diagnosis because troubleshooting involves internal induction electronics.
Professional service is recommended when:
- CF7 repeatedly returns
- A burner LED shows the 3-blink indication
- One or more induction zones stop operating
- Internal harness connections require inspection
- PCB communication needs to be diagnosed
- A Cooktop Main PCB or Inverter PCB may require replacement
Induction appliances contain high-power electronics. Internal inspection and electrical testing should be performed only after appropriate electrical safety procedures are followed.
Key Point
CF7 indicates a communication error between the Cooktop Main PCB and the Left Inverter PCB.
LG identifies:
Error: Communication Error Between Cooktop Main PCB & Left Inverter PCB
Cause: Loose connector connection or PCB failure
Additional indication: Burner may show a 3-blink code on the burner LED indicator
Solution: Check the harness for poor connections; replace the failed PCB if necessary.
CF7 does not automatically mean the Left Inverter PCB must be replaced. The communication harness and connections should be checked first.
CF8 — Communication Error Between Cooktop Main PCB & Right Inverter PCB
The CF8 error code indicates a communication problem between the Cooktop Main PCB and the Right Inverter PCB in an LG induction range or cooktop.
The Cooktop Main PCB and inverter electronics must continuously exchange control information for the induction cooking system to operate correctly. If communication between the main cooktop control and the right inverter electronics is interrupted, the appliance may detect the abnormal condition and display CF8.
According to LG diagnostic information, the primary causes are a loose connector connection or PCB failure.
What the CF8 Error Code Means
An LG induction cooking system can use several electronic control assemblies that perform different functions.
The Cooktop Main PCB coordinates overall cooktop operation, while the Right Inverter PCB controls high-power induction electronics associated with its portion of the cooking system.
These boards must communicate through an electrical harness and connectors.
The CF8 communication path can be represented as:
Cooktop Main PCB ↔ Wiring Harness / Connectors ↔ Right Inverter PCB
If communication is lost anywhere along this path, CF8 may appear.
This means CF8 is primarily a communication-system fault, rather than an individual burner temperature sensor or IGBT error.
Common Causes
LG identifies the primary causes of CF8 as:
- Loose connection at a connector
- PCB failure
When diagnosing the complete communication circuit, attention should therefore be given to:
- Loose harness connectors
- Connector not fully seated
- Poor terminal contact
- Damaged communication wiring
- Broken conductors
- Damaged connector terminals
- Cooktop Main PCB
- Right Inverter PCB
Because a poor connection can interrupt communication between otherwise functional electronic boards, CF8 does not automatically mean the Right Inverter PCB needs to be replaced.
The harness and connectors should be checked before an expensive electronic board is replaced.
3-Blink Burner LED Indicator
LG provides an additional diagnostic clue for CF8.
According to the source, the burner may show a:
3-blink code on the burner LED indicator.
This blinking indication can accompany the communication fault and may provide additional confirmation during diagnosis.
If CF8 appears, note whether one of the burner indicators is also blinking three times.
The exact indicator behavior and affected cooking zones can depend on the appliance configuration, so the complete model number should still be used when performing detailed diagnosis.
What You Can Check
Before internal service, record as much information as possible about when CF8 appears.
Useful observations include:
- Whether CF8 appears immediately after power-up
- Whether it appears only when an induction zone is used
- Which cooking zones were operating
- Whether one or more cooking zones stop heating
- Whether a burner LED produces the 3-blink indication
- Whether CF8 disappears after restarting the appliance
- Whether the code repeatedly returns
- The complete model number of the appliance
If internal inspection is performed by a qualified technician, attention should first be directed toward the communication harness between the Cooktop Main PCB and Right Inverter PCB.
Check the Wiring Harness and Connectors
LG’s specified repair direction begins with checking for a:
Poor connection of the harness.
Inspect the communication wiring and connectors for conditions such as:
- Loose connector
- Partially seated connector
- Bent terminal
- Backed-out terminal
- Broken wire
- Damaged harness
- Burned connection
- Poor electrical contact
Both ends of the communication harness should be inspected:
Cooktop Main PCB side
and
Right Inverter PCB side
A connector that appears installed may still have a poor terminal connection, so the connector and individual terminals may require closer inspection.
Cooktop Main PCB vs. Right Inverter PCB
If the harness and connectors are secure and no wiring problem is found, the communication fault may involve one of the electronic boards.
The possible communication path is:
Cooktop Main PCB → Harness → Right Inverter PCB
Because either electronic board can be involved, CF8 alone should not be interpreted as proof that the Right Inverter PCB has failed.
LG’s diagnostic guidance is to:
Check for poor connection of harness or replace PCB.
The failed board should therefore be identified through proper diagnosis before replacement.
CF7 vs. CF8
CF7 and CF8 form a pair of induction inverter communication errors:
CF7 → Communication Error Between Cooktop Main PCB & Left Inverter PCB
CF8 → Communication Error Between Cooktop Main PCB & Right Inverter PCB
Both codes can involve:
- Poor harness connection
- Connector problems
- PCB failure
- 3-blink burner LED indication
The important difference is which inverter PCB has lost communication with the Cooktop Main PCB.
This distinction helps direct inspection toward the correct side of the induction electronics.
CF5–CF8 Error Group
The CF5 through CF8 codes now form two related but distinct pairs:
CF5 → Left Inverter Board IGBT Error
CF6 → Right Inverter Board IGBT Error
CF7 → Main PCB ↔ Left Inverter PCB Communication Error
CF8 → Main PCB ↔ Right Inverter PCB Communication Error
This distinction is important.
CF5 and CF6 indicate IGBT/inverter power-electronics faults.
CF7 and CF8 indicate communication faults between electronic boards.
The diagnostic procedures should therefore not be treated as interchangeable.
CF8 Diagnostic Sequence
A practical diagnostic sequence based on LG’s information is:
CF8 displayed
→ Check for 3-blink burner LED indication
→ Record which cooking zones are affected
→ Inspect the communication harness
→ Check the Cooktop Main PCB connector
→ Check the Right Inverter PCB connector
→ Inspect wiring and terminals for damage
→ Correct any poor connection
→ Test appliance operation
→ If CF8 returns, diagnose the PCBs
→ Replace the failed PCB if confirmed
This approach helps avoid replacing an electronic board when the actual problem is a loose or damaged connection.
Can You Clear the CF8 Code?
Disconnecting and restoring power may temporarily clear CF8 if the communication problem was caused by a temporary electronic interruption.
However, a reset cannot repair a persistent:
- Loose connector
- Damaged wiring harness
- Broken terminal
- Poor electrical connection
- Failed Cooktop Main PCB
- Failed Right Inverter PCB
If CF8 repeatedly returns, the communication circuit should be diagnosed.
Repeated power resets should not be used as a substitute for correcting an underlying connection or PCB problem.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when CF8 repeatedly returns or troubleshooting requires access to the induction electronics.
This may involve:
- Opening the cooktop or range
- Inspecting internal harnesses
- Checking PCB connectors
- Testing communication wiring
- Diagnosing the Cooktop Main PCB
- Diagnosing the Right Inverter PCB
- Replacing an electronic control board
Induction appliances contain high-power electronic circuits. Internal diagnosis should be performed only by someone qualified to safely service induction cooking equipment.
Key Point
CF8 indicates a communication error between the Cooktop Main PCB and the Right Inverter PCB.
LG identifies:
Error: Communication Error Between Cooktop Main PCB & Right Inverter PCB
Cause: Loose connector connection or PCB failure
Additional indication: Burner may show a 3-blink code on the burner LED indicator
Solution: Check the harness for poor connections or replace the failed PCB.
CF8 does not automatically mean the Right Inverter PCB has failed. The wiring harness and connectors should be checked first, followed by PCB diagnosis if the communication error remains.
CF9 — Flex Top Sensor Failure
The CF9 error code indicates a failure involving the Flex Top Sensor circuit on an LG range or cooktop.
According to LG diagnostic information, CF9 can occur when the Left CTS Top Thermistor is open or shorted. The diagnostic procedure focuses on the top sensor connection, sensor resistance, thermal fuse circuit on applicable sensors, and the electronic PCB if the sensor tests correctly.
What the CF9 Error Code Means
The top sensor is used by the cooktop electronics to monitor temperature conditions associated with the cooking surface.
If the control detects an open or shorted thermistor circuit, the expected temperature signal is no longer available and CF9 may be displayed.
LG identifies the cause as:
Open or Shorted Left CTS Top Thermistor.
This means diagnosis should not begin by automatically replacing the PCB. The sensor circuit and its electrical connection should be checked first.
Depending on the sensor configuration, diagnosis may involve a single-burner top sensor or a sensor associated with the Flex Burner system.
Common Causes
Possible causes of CF9 include:
- Open Left CTS Top Thermistor
- Shorted Left CTS Top Thermistor
- Loose top sensor connection
- Poor connector contact
- Damaged sensor wiring
- Temperature sensor outside the specified resistance range
- PCB problem when the sensor tests correctly
The direct diagnostic procedure specifically instructs the technician to check the Top Sensor connection for an open condition and the Top Sensor resistance for a short condition.
Check the CN11T Connector
One of the first checks specified for CF9 is the CN11T connector.
LG instructs:
Check connector CN11T and make sure it is connected properly.
A loose or improperly seated connection can interrupt the thermistor circuit and create an apparent sensor failure even if the sensor itself is still functional.
When the appliance is safely disconnected from power and accessed by a qualified technician, inspect the connector for:
- Connector not fully seated
- Loose terminals
- Damaged connector housing
- Backed-out terminals
- Damaged wiring
- Poor electrical contact
The connection should be verified before replacing either the sensor or PCB.
Single Burner Top Sensor
LG describes a Top Sensor for Single Burner located in the center of the burners.
This sensor uses four wires:
- Two black wires
- Two white wires
The two black wires are the temperature sensor circuit.
LG specifies approximately:
50–60 kΩ at room temperature, approximately 70°F (21°C).
A measurement substantially outside this expected range may indicate a defective thermistor.
Check the Thermal Fuse
On the four-wire single-burner sensor, the two white wires serve a different purpose.
They are connected to the:
Thermal Fuse
According to the source, the thermal fuse circuit should read:
Closed.
This distinction is important when testing the four-wire sensor:
Black wires → Temperature sensor / thermistor
White wires → Thermal fuse
The two circuits should not be interpreted as the same component when taking resistance or continuity measurements.
Flex Burner Sensor
LG also describes a separate Sensor for Flex Burner.
This sensor is located between the front and rear burners and is used when the burners are bridged together.
Unlike the four-wire single-burner sensor, the Flex Burner sensor has only:
Two black wires
These are the wires used for the resistance test.
LG specifies approximately:
50–60 kΩ at room temperature, approximately 70°F (21°C).
This makes it important to first identify which sensor configuration is installed before interpreting the wiring.
How to Test the CF9 Sensor Circuit
A practical diagnostic sequence based on the source is:
CF9 displayed
→ Check CN11T connector
→ Identify the installed top sensor configuration
→ Check the black sensor wires
→ Verify approximately 50–60 kΩ at 70°F
→ On a four-wire sensor, check the two white thermal-fuse wires for continuity
→ Determine whether the sensor is within specification
→ Evaluate the PCB if the sensor tests correctly
This sequence separates a sensor problem from an electronic control problem.
Sensor vs. PCB Diagnosis
LG provides a particularly useful decision point for CF9.
If the sensor resistance is correct:
Replace the PCB.
If the sensor resistance is outside specification:
Replace the Sensor.
This makes resistance testing important before replacing the electronic control.
The diagnostic logic can be summarized as:
Sensor out of specification → Sensor is the repair direction
Sensor tests correctly → PCB becomes the repair direction
The appropriate replacement part should always be confirmed using the complete model number.
CF9 vs. CF7 and CF8
CF9 belongs to a different diagnostic category from the preceding communication errors.
CF7 → Cooktop Main PCB ↔ Left Inverter PCB Communication Error
CF8 → Cooktop Main PCB ↔ Right Inverter PCB Communication Error
CF9 → Flex Top Sensor Failure / Left CTS Top Thermistor Open or Shorted
CF7 and CF8 primarily direct diagnosis toward communication harnesses and PCBs.
CF9 directs diagnosis toward a temperature sensor circuit, including the thermistor resistance and, where applicable, the thermal fuse circuit.
The diagnostic procedures should therefore not be treated as interchangeable.
Can You Clear the CF9 Code?
Disconnecting and restoring power may restart the electronic controls, but it cannot repair an open or shorted thermistor circuit.
If CF9 returns, especially during cooktop operation, the top sensor circuit should be diagnosed.
A persistent CF9 condition may require checking:
- CN11T connection
- Sensor resistance
- Thermal fuse continuity on applicable sensors
- Sensor wiring
- PCB
Repeatedly resetting the appliance without correcting the underlying electrical condition is unlikely to provide a permanent solution.
When Professional Diagnosis Is Recommended
CF9 troubleshooting involves internal cooktop components and electrical measurements.
Professional diagnosis is recommended when the repair requires:
- Opening the cooktop or range
- Accessing CN11T
- Identifying the top sensor configuration
- Measuring thermistor resistance
- Testing thermal fuse continuity
- Inspecting internal wiring
- Diagnosing or replacing the PCB
The appliance should be disconnected from power before resistance or continuity measurements are performed.
Key Point
CF9 indicates a Flex Top Sensor Failure involving an open or shorted Left CTS Top Thermistor.
LG’s diagnostic information specifies:
CN11T: Verify the connector is properly connected
Top Sensor: Approximately 50–60 kΩ at 70°F (21°C)
Four-wire sensor black wires: Thermistor circuit
Four-wire sensor white wires: Thermal fuse — should read closed
Flex Burner sensor: Two black wires — approximately 50–60 kΩ at 70°F
Sensor out of specification: Replace the sensor
Sensor tests correctly: Replace the PCB
This makes CF9 a sensor-circuit diagnosis where the resistance measurement is particularly important for determining whether the sensor or PCB is the appropriate repair direction.
CFA — Over Current Error
The CFA error code indicates an over-current condition in the induction inverter system of an LG range or cooktop.
According to LG diagnostic information, the cause of the CFA error is a defective Inverter PCB. The specified repair solution is to replace the Inverter PCB.
Unlike the CF1–CF4 codes, which involve individual induction burner temperature sensor circuits, CFA directs diagnosis toward the inverter electronics responsible for controlling induction power.
What the CFA Error Code Means
The inverter system is responsible for controlling the electrical power required by the induction cooking system.
Induction appliances rely on high-power electronic components to rapidly control current supplied to the induction coils. The inverter PCB manages this power electronically rather than using a conventional resistive heating element.
CFA indicates that the induction control system has detected an over-current fault associated with the inverter electronics.
LG identifies the error simply as:
Over Current Error
and identifies the cause as:
Defective Inverter PCB.
This makes CFA primarily an inverter-board-level fault rather than an individual temperature sensor, burner switch, or communication error.
What Is an Over-Current Condition?
An over-current condition means that the electronic power-control system has detected current outside the operating condition expected by the appliance.
In an induction system, the inverter electronics operate under substantial electrical loads while controlling the electromagnetic energy used to heat cookware.
The control system is designed to monitor abnormal electrical conditions that could prevent safe or reliable operation.
When the condition associated with CFA is detected, the appliance may stop or restrict induction operation and display the error rather than continuing normal cooking.
For this specific code, LG directs the repair toward the Inverter PCB rather than providing a separate sensor or wiring diagnostic procedure.
Common Cause
For CFA, the direct LG diagnostic information lists one cause:
Defective Inverter PCB.
This is considerably more specific than codes such as CF7 or CF8, where a communication problem can be caused by either a poor harness connection or PCB failure.
For CFA, the source does not provide a list of alternative sensor, harness, or connector faults.
Therefore, additional causes should not be assumed without model-specific diagnostic information.
Symptoms That May Accompany CFA
Because CFA involves the inverter power electronics, the induction cooking system may be unable to operate normally when the fault is present.
Depending on the particular model and configuration, the user may observe conditions such as:
- CFA appearing on the display
- Induction heating stopping
- A cooking zone failing to operate normally
- The cooktop interrupting operation
- The error returning when induction heating is attempted
The exact behavior can vary by model, so the displayed code should be considered together with the appliance model number and actual symptoms.
What You Can Check
CFA is not primarily a user-serviceable error.
Before arranging internal diagnosis, useful information to record includes:
- The exact CFA code
- Which cooking zones were operating
- Whether the code appeared immediately or after heating began
- Whether the cooktop stopped heating
- Whether CFA returns after restarting the appliance
- The complete LG model number
This information can help identify the appropriate inverter assembly and determine whether additional model-specific diagnostic procedures apply.
Internal testing should only be performed by someone qualified to service induction power electronics.
Inverter PCB Diagnosis
The CFA diagnostic path differs from many of the earlier CF codes.
For example:
CF1–CF4
→ Individual induction temperature sensor circuits
CF7–CF8
→ Communication between Cooktop Main PCB and Inverter PCB
CF9
→ Top sensor / thermistor circuit
CFA
→ Inverter PCB over-current fault
For CFA, LG does not specify a thermistor resistance measurement, 5 VDC sensor supply check, or communication-harness test on the direct code page.
Instead, the source identifies the Inverter PCB itself as defective.
Inverter PCB Replacement
LG’s specified solution for CFA is:
Replace Inverter PCB.
The correct inverter board should be identified using the complete appliance model number before replacement.
Induction ranges can contain multiple electronic assemblies, and visually similar boards are not necessarily interchangeable between models.
For this reason, the exact model and appropriate service information should be used to identify the correct replacement component.
CFA vs. CF5 and CF6
CFA, CF5, and CF6 all involve induction inverter electronics, but they should not be treated as identical codes.
CF5 → Left Inverter Board IGBT Error
CF6 → Right Inverter Board IGBT Error
CFA → Over Current Error / Defective Inverter PCB
CF5 and CF6 identify an IGBT fault associated with a specific left or right inverter board.
CFA identifies an over-current fault and the direct source identifies a defective Inverter PCB as the cause.
This distinction is useful when diagnosing closely related induction electronics errors.
Can You Clear the CFA Code?
Disconnecting power may restart the electronic control system and remove the code temporarily.
However, a reset does not repair a defective inverter PCB.
Because LG identifies the cause of CFA as a defective Inverter PCB, a code that returns after restarting the appliance requires further diagnosis and repair rather than repeated resets.
If CFA repeatedly appears when induction heating is attempted, continued power cycling should not be considered a permanent solution.
When Professional Diagnosis Is Recommended
CFA should generally be treated as a professional repair issue because it involves the high-power inverter electronics of an induction appliance.
Professional service is recommended when:
- CFA repeatedly returns
- Induction heating stops
- One or more cooking zones fail to operate
- The inverter electronics require inspection
- The Inverter PCB requires replacement
Induction inverter systems operate with potentially hazardous electrical energy. Internal testing, disassembly, and PCB replacement should be performed by someone qualified to safely service induction cooking appliances.
Key Point
CFA indicates an Over Current Error involving the induction inverter system.
LG’s direct diagnostic information specifies:
Error: Over Current Error
Cause: Defective Inverter PCB
Solution: Replace Inverter PCB.
Unlike several other CF codes, the CFA source does not provide additional sensor resistance, voltage, or harness specifications. The repair direction given for this code is specifically the Inverter PCB.
CFC — Over Voltage Error
The CFC error code indicates that the LG range or oven has detected an over-voltage condition in the incoming electrical power supply.
Unlike many CF-series errors that involve induction temperature sensors, inverter boards, or communication between electronic modules, CFC directs attention to the electrical supply coming from the home.
According to LG diagnostic information, the cause of CFC is that the voltage from the customer’s house is too high. LG recommends having an electrician check the home’s electrical power.
What the CFC Error Code Means
LG ranges and ovens are designed to operate within specified electrical supply conditions.
When the appliance detects incoming voltage that is too high, the electronic control system may display CFC rather than continuing normal operation under an abnormal power condition.
LG identifies CFC as:
Over Voltage Error
with the cause:
Voltage from customer’s house is too high.
This distinction is important because CFC should not immediately be treated as an appliance component failure.
The problem may originate outside the appliance, in the electrical supply feeding the range or oven.
Common Cause
For CFC, the direct LG diagnostic information identifies one primary cause:
- Incoming voltage from the home’s electrical system is too high.
The source does not identify a temperature sensor, inverter PCB, induction coil, or another internal appliance component as the primary cause of this code.
For that reason, replacing internal components before verifying the incoming electrical supply would not be an appropriate first diagnostic step.
Why Correct Supply Voltage Matters
Ranges and ovens can contain sensitive electronic controls as well as high-power heating or induction circuits.
The appliance’s electronic systems are designed around a specified input voltage. If the incoming voltage is substantially different from what the appliance is designed to receive, electronic controls and power circuits may not operate as intended.
An over-voltage condition can therefore affect normal appliance operation and should be investigated rather than repeatedly clearing the error and continuing to use the appliance.
For CFC, diagnosis should begin with the power source, not with random replacement of internal appliance parts.
What You Can Check
If CFC appears, first record:
- The exact CFC code
- When the code appeared
- Whether it appeared immediately after power-up
- Whether other electrical problems occurred around the same time
- Whether the code returns after restarting the appliance
- The complete LG model number
You can also check whether there have recently been:
- Electrical service changes
- Breaker or panel work
- Outlet or range-circuit work
- Appliance installation or reconnection
- Other unusual electrical behavior in the home
However, determining whether the supply voltage is actually too high requires proper electrical measurement.
Have the Incoming Power Supply Checked
LG’s specified solution for CFC is:
The customer should have an electrician check the house power.
A qualified electrician can verify whether the electrical circuit supplying the appliance is providing the correct voltage for that particular LG model.
Depending on the appliance and installation, this may require checking the supply at:
- Electrical panel
- Circuit breaker
- Range receptacle
- Junction box
- Appliance connection point
The exact required voltage should be determined from the appliance rating information and model-specific documentation rather than assumed.
Do Not Assume the Main PCB Has Failed
Because CFC appears on an electronically controlled appliance, it may be tempting to assume that the Main PCB or another control board is defective.
However, the direct LG CFC information specifically identifies high house voltage as the cause.
Therefore, the incoming electrical supply should be verified before diagnosing internal electronic components.
This can prevent unnecessary replacement of expensive appliance parts when the actual problem is with the home’s electrical system.
CFC vs. CFA
Although CFA and CFC are both part of the CF-series, they represent very different electrical problems.
CFA — Over Current Error
→ LG identifies a defective Inverter PCB.
CFC — Over Voltage Error
→ LG identifies excessive voltage from the customer’s house.
This distinction is particularly important.
An over-current error within the induction inverter electronics is not the same as an over-voltage condition in the incoming electrical supply.
The two codes therefore require different diagnostic approaches.
CFC Diagnostic Sequence
A practical diagnostic sequence for CFC is:
CFC displayed
→ Record the error and appliance model number
→ Avoid assuming an internal component has failed
→ Verify the appliance’s required electrical supply
→ Have incoming voltage professionally measured
→ Inspect the home’s appliance circuit if voltage is abnormal
→ Correct the electrical supply problem
→ Test appliance operation again
If the incoming supply is corrected but CFC continues to appear, further model-specific appliance diagnosis may then be appropriate.
Can You Clear the CFC Code?
Disconnecting and restoring power may clear the code from the display temporarily.
However, a reset cannot correct an electrical supply that remains outside the appliance’s acceptable operating conditions.
If the incoming voltage is still too high, CFC may return after power is restored.
For this reason, repeatedly resetting the range or oven should not be used as a substitute for checking the home’s electrical supply.
When Professional Diagnosis Is Recommended
CFC should be investigated by a qualified professional because confirming an over-voltage condition requires measurements on the appliance’s mains electrical supply.
LG specifically recommends having an electrician check the house power.
Professional electrical inspection is particularly appropriate when:
- CFC repeatedly returns
- The appliance behaves abnormally after installation
- Recent electrical work was performed
- Other electrical devices show unusual behavior
- Supply voltage needs to be measured
- The range circuit, receptacle, breaker, or electrical panel requires inspection
Mains-voltage testing should not be performed by someone who is not qualified to work safely with household electrical systems.
Key Point
CFC indicates an Over Voltage Error.
LG’s direct diagnostic information specifies:
Error: Over Voltage Error
Cause: Voltage from the customer’s house is too high
Solution: Have an electrician check the home’s electrical power.
CFC should therefore be approached as a power-supply problem first, rather than assuming that an internal range or oven component needs replacement.
CFE — Blower Fan Error
The CFE error code indicates a problem with the blower fan system in an LG induction range or cooktop.
The blower fan helps manage airflow and temperature around the induction electronics. If the electronic control detects that the blower fan system is not operating as expected, the appliance may display CFE.
According to LG diagnostic information, the fault can be caused by a defective fan motor or missing 12 VDC power to the fan circuit.
What the CFE Error Code Means
Induction cooking systems contain high-power electronic components that generate heat during normal operation.
The appliance uses a blower fan to move air through the cooktop electronics and help maintain appropriate operating temperatures.
If the blower fan cannot operate correctly, the induction electronics may not receive the cooling airflow they require.
For CFE, LG identifies the condition specifically as:
Blower Fan Error
and lists the cause as a bad fan motor or missing 12 VDC.
This means the code does not automatically prove that the blower fan motor itself has failed. The electrical supply to the motor and the associated wiring connections also need to be considered.
Common Causes
The primary causes of CFE include:
- Defective blower fan motor
- Missing 12 VDC supply to the fan
- Poor harness connection
- Loose electrical connector
- Problem with the fan’s electrical circuit
- Cooktop Inverter PCB not providing the required voltage
The direct diagnostic information specifically instructs technicians to verify both 12 VDC from the Cooktop Inverter PCB and the harness connections.
What You Can Check
Before internal electrical testing, note how the appliance behaves when CFE appears.
Useful observations include:
- Whether CFE appears immediately after the cooktop is turned on
- Whether it appears only after cooking for some time
- Whether induction heating stops
- Whether the blower fan can be heard operating
- Whether the error disappears after the appliance cools
- Whether CFE returns after power is restored
- Which cooking zones were operating when the error appeared
These observations do not replace electrical diagnosis, but they can provide useful information about the circumstances under which the blower fan fault is detected.
Check the Blower Fan Motor
One of the two causes specifically identified by LG is a bad fan motor.
The blower fan assembly should therefore be inspected for proper operation.
A qualified technician may check:
- Whether the fan operates when commanded
- Fan motor electrical connections
- Fan wiring
- Connector condition
- Physical condition of the fan assembly
If the motor is receiving the correct electrical supply but does not operate properly, the fan motor itself becomes a likely repair direction.
However, the voltage supply should be verified before concluding that the motor is defective.
Check for 12 VDC From the Cooktop Inverter PCB
LG specifically instructs technicians to:
Check for 12 VDC from the Cooktop Inverter PCB.
This is one of the most important diagnostic checks for CFE.
The diagnostic logic is essentially:
Blower fan not operating
→ Determine whether the motor receives its required 12 VDC supply.
If the correct voltage is present but the fan motor does not operate, the motor itself requires further evaluation.
If the expected 12 VDC is missing, diagnosis should move toward the wiring, connectors, and Cooktop Inverter PCB rather than automatically replacing the blower motor.
Check the Harness Connections
LG also specifically instructs technicians to:
Check for proper harness connections.
This is important because a loose or damaged electrical connection can interrupt the fan’s power circuit and create the same CFE condition as a failed motor.
Inspect the relevant connections for:
- Loose connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Bent or backed-out terminal
- Burned connector
- Poor terminal contact
Connections should be checked both at the blower fan and at the relevant cooktop electronics.
A wiring or connector problem should be corrected before replacing electronic components.
Fan Motor vs. Inverter PCB Diagnosis
CFE requires distinguishing between two primary possibilities:
Fan-side problem
→ The blower fan motor is defective.
Power/control-side problem
→ The expected 12 VDC supply is missing.
A practical diagnostic sequence is:
CFE displayed
→ Inspect blower fan and harness
→ Verify connectors are properly seated
→ Check for 12 VDC from Cooktop Inverter PCB
→ If voltage is present, evaluate blower fan motor
→ If voltage is missing, investigate wiring and Cooktop Inverter PCB
This prevents unnecessary replacement of the blower fan when the actual problem is the electrical supply to the motor.
Why the Blower Fan Is Important
The blower fan is part of the thermal-management system for the induction electronics.
Induction inverter circuitry handles substantial electrical power and produces heat during operation. Proper airflow helps prevent excessive temperature buildup around these electronic components.
For this reason, a persistent blower fan error should not simply be ignored while continuing to operate the cooktop.
If the fan system is not operating correctly, the underlying problem should be diagnosed and repaired.
CFE vs. Other CF-Series Codes
CFE belongs to a different diagnostic category from the preceding CF codes.
CF5 / CF6 → Inverter board IGBT errors
CF7 / CF8 → Main PCB ↔ Inverter PCB communication errors
CF9 → Flex Top Sensor failure
CFA → Over Current Error
CFC → Over Voltage Error
CFE → Blower Fan Error
CFE specifically directs troubleshooting toward the blower fan motor, its 12 VDC supply, harness connections, and Cooktop Inverter PCB.
This is why diagnostic procedures from the temperature-sensor or communication codes should not automatically be applied to CFE.
Can You Clear the CFE Code?
Disconnecting and restoring power may restart the control system and temporarily remove CFE from the display.
However, a reset cannot repair:
- Defective blower fan motor
- Missing 12 VDC supply
- Loose harness connector
- Damaged wiring
- Cooktop Inverter PCB problem
If CFE returns, particularly during induction cooking, the blower fan circuit should be diagnosed.
Repeated resets are not a permanent solution to a persistent fan-system fault.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended for CFE because proper troubleshooting may require access to the induction electronics and live DC voltage measurements.
A technician may need to:
- Access the blower fan
- Inspect the fan motor
- Check internal harness connections
- Measure the 12 VDC supply
- Inspect wiring continuity
- Diagnose the Cooktop Inverter PCB
Induction appliances contain high-power electrical circuits, so internal testing should only be performed by someone qualified to work safely with induction cooking systems.
Key Point
CFE indicates a Blower Fan Error.
LG specifies:
Error: Blower Fan Error
Possible cause: Bad fan motor or missing 12 VDC
Voltage check: Verify 12 VDC from the Cooktop Inverter PCB
Harness check: Verify proper harness connections.
CFE does not automatically mean the blower fan motor has failed. The 12 VDC supply and harness connections should also be checked before determining which component requires repair.
CFF — Box Fan Error
The CFF error code indicates a problem with the box fan system in an LG range or cooktop.
The box fan is part of the cooling system used to manage temperatures around the cooktop’s electronic components. If the control system detects that the fan is not operating correctly, the appliance may display CFF.
According to LG diagnostic information, the problem may be caused by a defective fan motor or missing 12 VDC power. The diagnostic procedure includes checking the voltage supplied by the Cooktop System PCB and measuring the fan motor winding.
What the CFF Error Code Means
Electronic components inside an induction cooking system generate heat during normal operation.
Cooling fans are used to move air around these components and help maintain acceptable operating temperatures.
CFF specifically identifies a problem with the box fan.
LG identifies the code as:
Box Fan Error
and lists the cause as:
Fan motor is bad or is missing 12 VDC.
This means CFF does not automatically confirm that the fan motor itself has failed.
The fan may be unable to operate because it is not receiving the required voltage from the Cooktop System PCB.
Common Causes
Based on LG’s diagnostic information, the primary possibilities are:
- Defective box fan motor
- Missing 12 VDC supply
- Problem in the fan motor circuit
- Cooktop System PCB not supplying the required voltage
The fan motor winding also has a specified resistance value that can be checked during diagnosis.
The important distinction is between a fan motor problem and a power-supply/control problem.
What You Can Check
Before internal testing, observe when CFF appears and how the appliance behaves.
Useful information includes:
- Whether CFF appears immediately after power-up
- Whether it appears after the cooktop has been operating
- Whether induction heating stops
- Whether the cooling fan can be heard operating
- Whether the error appears only after extended cooking
- Whether CFF returns after the appliance is restarted
- The complete model number of the range or cooktop
These observations can help a technician reproduce the fault, but electrical measurements are needed to determine whether the fan motor or its power supply is responsible.
Check for 12 VDC From the Cooktop System PCB
LG specifically instructs technicians to check for:
12 VDC from the Cooktop System PCB.
This is an important diagnostic step because the box fan cannot operate correctly if its required power supply is missing.
The basic diagnostic distinction is:
12 VDC present
→ The fan motor itself requires further testing.
12 VDC missing
→ Diagnosis should move toward the electrical supply circuit and Cooktop System PCB.
This prevents unnecessary replacement of the fan motor when the actual problem is that the control system is not supplying the required voltage.
Check the Fan Motor Winding
LG also provides a specific resistance value for the box fan motor winding:
4.1 MΩ
The fan motor winding should be measured and compared with this specification.
A measurement significantly outside the specified value can indicate a problem with the fan motor.
Resistance testing should be performed with the appliance disconnected from electrical power and according to the appropriate service procedure.
Because specifications and wiring arrangements can vary between models, the complete appliance model number should be confirmed before internal diagnosis.
Fan Motor vs. Cooktop System PCB Diagnosis
CFF requires distinguishing between two primary fault paths.
Fan-side problem:
The required electrical supply is available, but the fan motor does not meet the expected electrical specification or operate correctly.
Control-side problem:
The fan cannot operate because the expected 12 VDC from the Cooktop System PCB is missing.
A practical diagnostic sequence is:
CFF displayed
→ Inspect the box fan system
→ Check electrical connections
→ Verify 12 VDC from the Cooktop System PCB
→ Check fan motor winding for 4.1 MΩ
→ Compare measurements with specification
→ Determine whether the problem is on the fan or control side
This approach helps avoid replacing components without first identifying which part of the circuit is responsible.
Why the Box Fan Is Important
The box fan contributes to thermal management inside the cooktop.
Induction cooking systems contain power electronics that can generate significant heat during operation. Adequate airflow helps these components remain within their intended operating temperature range.
A box fan that cannot operate correctly may therefore interfere with normal operation of the induction system.
For this reason, a persistent CFF code should be diagnosed rather than repeatedly cleared and ignored.
CFE vs. CFF
CFE and CFF are closely related because both involve cooling fans, but they should remain separate entries.
CFE → Blower Fan Error
CFF → Box Fan Error
The diagnostic information also differs.
For CFE, LG directs diagnosis toward the blower fan and its 12 VDC supply.
For CFF, LG provides both:
Cooktop System PCB output: 12 VDC
Box fan motor winding: 4.1 MΩ
Therefore, the two codes should not be treated as interchangeable even though both belong to the cooktop cooling system.
CFF Diagnostic Sequence
A useful diagnostic sequence for CFF is:
CFF displayed
→ Record the appliance model number
→ Determine whether the box fan is operating
→ Inspect the fan and electrical connections
→ Check for 12 VDC from the Cooktop System PCB
→ Measure the fan motor winding
→ Compare the winding measurement with 4.1 MΩ
→ Determine whether the fan motor or its power/control circuit requires further diagnosis
This provides a more reliable repair direction than replacing the fan immediately after seeing CFF.
Can You Clear the CFF Code?
Disconnecting and restoring power may restart the electronic control system and temporarily remove CFF from the display.
However, a reset cannot repair:
- A defective fan motor
- An abnormal fan motor winding
- Missing 12 VDC supply
- A persistent electrical or control problem
If CFF returns, the box fan circuit should be diagnosed.
Repeated power resets should not be considered a permanent solution to a persistent cooling-system fault.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended because CFF troubleshooting requires access to internal cooktop electronics and electrical measurements.
A technician may need to:
- Access the box fan
- Inspect fan operation
- Measure the fan motor winding
- Check the 12 VDC supply
- Inspect internal connections
- Diagnose the Cooktop System PCB
Induction cooking appliances contain high-power electronics, so internal diagnosis should only be performed by someone qualified to safely service these systems.
Key Point
CFF indicates a Box Fan Error.
LG’s diagnostic information specifies:
Error: Box Fan Error
Possible cause: Defective fan motor or missing 12 VDC
Cooktop System PCB: Check for 12 VDC
Fan motor winding: Check for 4.1 MΩ
CFF does not automatically mean the fan motor needs replacement. Both the motor winding and its 12 VDC supplyshould be checked to determine which part of the circuit is responsible.
F1 — Upper Oven Thermistor Error
The F1 error code on most LG ranges and ovens indicates an Upper Oven Thermistor Error.
The oven control relies on the upper oven temperature sensor to provide temperature information to the Main PCB. When the Main PCB does not receive the expected signal from the Upper Oven Sensor, the appliance may display F1.
However, the meaning of F1 is model-dependent. On several older LG electric range models, F1 represents a Keypad Error instead of an upper oven temperature sensor problem.
What the F1 Error Code Means
For most LG range and oven models covered by this diagnostic information, F1 indicates that the Main PCB is not receiving a signal from the Upper Oven Sensor.
The Upper Oven Sensor, commonly referred to as an oven thermistor or temperature sensor, provides temperature feedback to the electronic control system.
The Main PCB uses this information to monitor oven temperature and control heating operation.
If the expected sensor signal is lost, the electronic control can no longer reliably determine the upper oven temperature and may display F1.
LG identifies the cause as:
No signal to Main PCB from the Upper Oven Sensor.
Important Exception for Older LG Electric Ranges
F1 does not mean Upper Oven Thermistor Error on every LG model.
LG specifically identifies these older electric range models:
- LRE3012
- LRE30451
- LRE30453
- LRE30757
On these models:
F1 = Keypad Error
LG directs technicians to the F3 Error Code troubleshooting procedure for diagnosing the keypad fault.
For all other models not included in this older-model list, the source directs troubleshooting toward the F1 Upper Oven Thermistor Error.
This is an important example of why the complete model number should always be checked before diagnosing an LG error code.
Common Causes
For models where F1 represents the Upper Oven Thermistor Error, diagnosis should focus on the signal path between the Upper Oven Sensor and Main PCB.
Possible areas requiring inspection include:
- Upper Oven Sensor
- Upper Oven Sensor connection
- Wiring between the sensor and Main PCB
- Loose electrical connector
- Poor terminal contact
- Main PCB connection
- Main PCB
The direct source specifically instructs technicians to check the Main PCB connections and Upper Oven Sensor connections.
This means F1 should not automatically be interpreted as proof that the temperature sensor itself has failed.
What Is the Upper Oven Thermistor?
The oven temperature sensor is a temperature-sensitive electrical component used by the electronic control system to monitor conditions inside the oven cavity.
As oven temperature changes, the electrical characteristics of the sensor change. The Main PCB interprets this information and uses it as part of the oven’s temperature-control process.
If the control loses the sensor signal, it may no longer have reliable temperature feedback.
F1 therefore represents a problem with the temperature-sensing circuit, rather than automatically identifying a failed heating element or another heating component.
What You Can Check
If F1 appears, first record:
- The exact F1 code
- Complete appliance model number
- Whether the appliance is a range or wall oven
- Whether it has separate upper and lower ovens
- When the error appears
- Whether the upper oven heats
- Whether the displayed temperature behaves abnormally
- Whether F1 returns after power is restored
The model number is particularly important because it determines whether F1 should be diagnosed as an Upper Oven Thermistor Error or Keypad Error.
Check the Upper Oven Sensor Connections
For most models, LG’s troubleshooting direction specifically includes checking the:
Upper Oven Sensor connections.
A sensor circuit can lose its signal because of an electrical connection problem even if the sensor itself has not failed.
A qualified technician should inspect the relevant circuit for conditions such as:
- Loose sensor connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Damaged terminals
- Poor electrical contact
- Heat-damaged connections
Any connection problem should be corrected before replacing the sensor or Main PCB.
Check the Main PCB Connections
LG also specifically instructs technicians to check the:
Main PCB connections.
The complete signal path can be thought of as:
Upper Oven Sensor → Wiring / Connectors → Main PCB
A failure anywhere along this path can prevent the Main PCB from receiving the expected temperature signal.
For this reason, F1 does not necessarily mean:
“Replace the oven temperature sensor.”
The sensor circuit and its connections should be diagnosed first.
Sensor vs. Main PCB Diagnosis
The direct F1 page does not provide a specific resistance value, connector pin measurement, or voltage specification for the Upper Oven Sensor.
Therefore, those values should be obtained from the service information for the specific LG model rather than borrowed from another error code or appliance model.
A reasonable diagnostic path based on LG’s information is:
F1 displayed
→ Verify model number
→ Determine whether the older-model keypad exception applies
→ For other models, inspect Upper Oven Sensor connections
→ Inspect wiring between sensor and Main PCB
→ Check Main PCB connections
→ Test the Upper Oven Sensor according to model-specific specifications
→ Evaluate the Main PCB if the sensor circuit tests correctly
This prevents unnecessary parts replacement based only on the F1 code.
F1 on Older Models — Keypad Diagnosis
If the appliance is one of the specified older electric ranges:
LRE3012, LRE30451, LRE30453, or LRE30757
do not follow the Upper Oven Sensor diagnostic path.
For these models:
F1 = Keypad Error
and LG specifically directs troubleshooting to the F3 Error Code procedure.
This exception should be checked before ordering an oven temperature sensor or Main PCB.
Can You Clear the F1 Code?
Disconnecting power may restart the electronic control system and temporarily clear F1.
However, a reset cannot repair a persistent problem involving:
- Upper Oven Sensor circuit
- Sensor wiring
- Loose electrical connection
- Main PCB connection
- Keypad fault on the specified older models
If F1 returns, record when it reappears and diagnose the appropriate circuit for the specific model.
Repeatedly resetting the appliance should not replace proper troubleshooting.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when F1 repeatedly returns or troubleshooting requires internal electrical testing.
A technician may need to:
- Verify the model-specific meaning of F1
- Access the Upper Oven Sensor
- Inspect sensor wiring
- Check electrical continuity
- Test the thermistor
- Inspect Main PCB connections
- Diagnose the Main PCB
- Diagnose the keypad circuit on applicable older models
Ovens and ranges contain mains-voltage circuits and high-temperature components, so internal diagnosis should be performed using appropriate electrical safety procedures.
Key Point
For most LG ranges and ovens, F1 indicates:
Error: Upper Oven Thermistor Error
Cause: Main PCB is receiving no signal from the Upper Oven Sensor
Initial checks: Main PCB connections and Upper Oven Sensor connections.
But there is an important model exception:
LRE3012 / LRE30451 / LRE30453 / LRE30757
→ F1 = Keypad Error
→ Follow the F3 troubleshooting procedure.
F10 — Upper Oven Door Locking System Failure
The F10 error code indicates a door locking system failure in the upper oven of an LG range or oven.
The door locking system is especially important during the Self Clean cycle, when the oven must confirm that the door is securely locked before allowing the high-temperature cleaning process to continue.
F10 appears when the control system does not detect the expected door lock switch condition at the beginning of Self Clean.
What the F10 Error Code Means
When a Self Clean cycle begins, the oven control activates the door locking mechanism and monitors the door lock system for confirmation that the door has reached the required locked position.
If the expected lock switch signal is not detected, the control cannot confirm that the upper oven door is properly locked.
The appliance may then stop the Self Clean sequence and display F10.
This makes F10 primarily a door lock system diagnostic code, rather than a heating, temperature sensor, or general control error.
Common Causes
The F10 diagnostic path should focus on the upper oven door locking system, including:
- Door Lock Motor
- Door lock switch
- Door Lock Motor connections
- Wiring between the locking system and Main PCB
- Loose or damaged connectors
- Main PCB connections
- Mechanical problems preventing the lock from reaching its correct position
The error does not automatically mean that the Door Lock Motor must be replaced. The electrical connections and operation of the complete locking system should be checked first.
What You Can Check
If F10 appears, record when the error occurs.
Useful observations include:
- Whether F10 appears specifically when Self Clean is started
- Whether the upper oven door attempts to lock
- Whether the locking mechanism can be heard operating
- Whether the door actually reaches the locked position
- Whether the lock indicator appears
- Whether the door remains unlocked
- Whether F10 returns every time Self Clean is selected
Because the source specifically describes the fault as occurring at the beginning of Self Clean, the timing of the error is particularly useful for diagnosis.
Check the Door Lock Motor Connections
The Door Lock Motor should be electrically connected to the control system so the oven can operate the locking mechanism during Self Clean.
Inspect the relevant connections for:
- Loose connectors
- Connector not fully seated
- Damaged wiring
- Broken conductors
- Burned terminals
- Poor terminal contact
- Damage around the Door Lock Motor assembly
A connection problem can prevent the locking mechanism from operating or prevent the control from detecting the expected lock condition.
Check the Main PCB Connections
The source also specifically directs technicians to check the Main PCB connections.
The control board must be able to operate the locking system and receive the appropriate door lock status information.
A simplified signal path is:
Main PCB → Door Lock Motor / Lock Mechanism → Door Lock Switch Feedback → Main PCB
A poor connection anywhere in this circuit can interfere with the locking sequence.
For this reason, wiring and connectors should be inspected before assuming that the Main PCB or Door Lock Motor has failed.
Check the Door Lock Motor Resistance
The direct F10 diagnostic information provides a specific resistance value for the Door Lock Motor:
2.6 kΩ
A qualified technician can measure the motor and compare the reading with this specification.
A measurement that does not correspond to the specified value may indicate a problem with the Door Lock Motor.
Resistance testing should be performed with power disconnected and according to appropriate electrical service procedures.
Check for 120 VAC
The F10 source also specifies:
120 VAC
as part of the Door Lock Motor diagnostic check.
This allows the technician to distinguish between a motor problem and a problem with the electrical supply/control circuit.
The basic diagnostic logic is:
Correct voltage supplied + motor does not operate correctly
→ Investigate the Door Lock Motor and locking mechanism.
Expected voltage missing
→ Investigate wiring, connections, and the control side of the circuit.
Because this measurement involves live mains voltage, it should only be performed by someone qualified to work safely on energized appliances.
Check the Door Lock Switch
The key condition behind F10 is that the door lock switch is not detected at the beginning of Self Clean.
Therefore, diagnosis should not focus exclusively on the motor.
The motor may physically move the locking mechanism, but the control must also receive confirmation that the required lock position has been reached.
A problem with the lock switch, its mechanical actuation, wiring, or signal path can prevent that confirmation.
This explains why an oven can potentially attempt to lock the door yet still display F10.
Electrical Fault vs. Mechanical Locking Problem
The F10 condition can be approached from two directions.
Electrical side:
- Door Lock Motor
- Motor power supply
- Door lock switch circuit
- Wiring and connectors
- Main PCB connections
Mechanical side:
- Lock mechanism does not move correctly
- Lock cannot reach its intended position
- Mechanical obstruction
- Door or latch alignment problem
A technician should determine whether the control is unable to operate the lock or whether the mechanism operates but the expected locked condition is not detected.
F10 Diagnostic Sequence
A practical diagnostic sequence is:
F10 displayed at the beginning of Self Clean
→ Confirm the problem involves the upper oven
→ Observe whether the door attempts to lock
→ Inspect the locking mechanism
→ Check Door Lock Motor connections
→ Check Main PCB connections
→ Verify the lock switch circuit
→ Check Door Lock Motor resistance for 2.6 kΩ
→ Check the specified 120 VAC supply during appropriate diagnosis
→ Determine whether the problem is the motor, lock mechanism, wiring, switch, or control circuit
This approach helps avoid replacing the Door Lock Motor solely because F10 appears.
Can You Clear the F10 Code?
Turning the appliance off and restoring power may reset the electronic control and temporarily clear F10.
However, resetting the oven cannot repair a persistent problem with the:
- Door Lock Motor
- Door lock switch
- Lock mechanism
- Wiring
- Electrical connections
- Main PCB circuit
If F10 returns when Self Clean is started, the door locking system should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when F10 repeatedly returns or the upper oven cannot confirm that its door is locked.
A technician may need to:
- Access the Door Lock Motor
- Inspect the lock mechanism
- Test the door lock switch
- Measure motor resistance
- Verify the 120 VAC motor supply
- Inspect wiring and connectors
- Check Main PCB connections
Because the diagnostic procedure can involve 120 VAC live-voltage testing, internal electrical measurements should only be performed by someone qualified to safely service ovens and ranges.
Key Point
F10 indicates an Upper Oven Door Locking System Failure.
The direct diagnostic information specifies:
Condition: Door lock switch not detected at the beginning of Self Clean
Connections: Check Main PCB and Door Lock Motor connections
Door Lock Motor resistance: 2.6 kΩ
Door Lock Motor voltage: 120 VAC
F10 does not automatically mean the Door Lock Motor has failed. The motor, lock switch, mechanical locking system, wiring, connections, and control circuit should be considered during diagnosis.
F11 — Lower Oven Door Locking System Failure
The F11 error code indicates a door locking system failure in the lower oven of an LG range or oven.
The lower oven door locking system must operate correctly during the Self Clean cycle. When Self Clean begins, the electronic control activates the locking mechanism and expects confirmation that the lower oven door has reached the locked position.
If the expected door lock switch condition is not detected, the appliance may stop the cleaning sequence and display F11.
What the F11 Error Code Means
F11 occurs when the door lock switch is not detected at the beginning of the Self Clean cycle for the lower oven.
During Self Clean, the oven reaches temperatures considerably higher than those used during normal cooking. The door locking system prevents the door from being opened during this process.
The control therefore needs confirmation from the locking system before Self Clean can proceed.
If that confirmation is missing, F11 may appear.
This makes F11 primarily a lower oven door lock system fault, rather than a temperature sensor, heating element, or general oven control error.
Common Causes
The F11 diagnostic path should focus on the lower oven door locking system, including:
- Door Lock Motor
- Door lock switch
- Door Lock Motor connections
- Main PCB connections
- Wiring between the locking system and control
- Loose or damaged connectors
- Mechanical problems with the door locking mechanism
The presence of F11 does not automatically prove that the Door Lock Motor itself has failed. The complete lock circuit should be evaluated.
What You Can Check
When F11 appears, note exactly when and how the error occurs.
Useful observations include:
- Whether F11 appears when Self Clean is started
- Whether the lower oven door attempts to lock
- Whether the lock motor can be heard operating
- Whether the lower oven door physically locks
- Whether the lock indicator changes
- Whether the locking mechanism moves partially
- Whether F11 returns every time Self Clean is selected
Because F11 is specifically associated with the beginning of Self Clean, the timing of the error can help distinguish a door lock problem from unrelated oven faults.
Check the Door Lock Motor Connections
The lower oven Door Lock Motor requires proper electrical connections to operate and complete the locking sequence.
Inspect the relevant circuit for:
- Loose connectors
- Connectors not fully seated
- Damaged wiring
- Broken conductors
- Burned or discolored terminals
- Poor terminal contact
- Damage around the Door Lock Motor assembly
A connection problem can prevent the motor from operating even when the motor itself is functional.
Check the Main PCB Connections
The Main PCB is part of the lower oven door locking control circuit and should also be checked for proper connections.
The basic operating sequence can be represented as:
Main PCB → Door Lock Motor / Lock Mechanism → Door Lock Switch Feedback → Main PCB
The control activates the locking mechanism and then needs confirmation that the expected door lock position has been reached.
A poor connection anywhere along this circuit can interfere with the locking sequence and result in F11.
Check the Door Lock Motor Resistance
LG provides a specific resistance specification for the Door Lock Motor:
2.6 kΩ
The motor can be tested and its resistance compared with this value.
If the motor winding does not correspond to the specified resistance, the Door Lock Motor may require further evaluation or replacement.
Resistance measurements should be performed with electrical power disconnected from the appliance.
Check for 120 VAC
The F11 diagnostic information also specifies:
120 VAC
for the Door Lock Motor circuit.
Checking whether the expected voltage reaches the motor can help distinguish between a motor problem and a power/control problem.
The diagnostic logic is:
120 VAC present but motor does not operate correctly
→ Investigate the Door Lock Motor and mechanical locking assembly.
120 VAC missing when the motor should be activated
→ Investigate wiring, connections, and the control side of the circuit.
Live-voltage testing involves a serious electrical hazard and should only be performed by a qualified appliance technician.
Check the Door Lock Switch
The defining condition behind F11 is not simply that the motor fails to turn.
The error occurs because the expected door lock switch condition is not detected.
This means the switch and its associated mechanism are important parts of the diagnostic process.
A problem may occur if:
- The locking mechanism does not reach the required position
- The switch does not change state
- The switch is not mechanically activated
- The switch circuit has a poor connection
- Wiring prevents the switch signal from reaching the control
Therefore, a Door Lock Motor that appears to move does not necessarily rule out an F11 fault.
Electrical vs. Mechanical Door Lock Problems
The lower oven locking system includes both electrical and mechanical components.
Electrical problems may involve:
- Door Lock Motor
- Door lock switch
- Motor power supply
- Wiring
- Connectors
- Main PCB connections
Mechanical problems may involve:
- Lock mechanism binding
- Lock not reaching its required position
- Misalignment
- Mechanical obstruction
- Damaged locking components
Diagnosis should determine whether the control cannot operate the locking system or whether the mechanism moves but fails to provide the expected locked-position confirmation.
F11 Diagnostic Sequence
A practical diagnostic sequence is:
F11 appears at the beginning of Self Clean
→ Confirm the error involves the lower oven
→ Observe whether the door attempts to lock
→ Inspect the mechanical locking system
→ Check Door Lock Motor connections
→ Check Main PCB connections
→ Check the door lock switch circuit
→ Measure Door Lock Motor resistance: 2.6 kΩ
→ Verify the specified 120 VAC during appropriate live diagnosis
→ Determine whether the motor, switch, wiring, mechanism, or control circuit is responsible
This sequence helps avoid replacing the Door Lock Motor before the rest of the locking circuit has been evaluated.
F10 vs. F11
F10 and F11 describe essentially the same type of door locking fault, but they apply to different oven cavities.
F10 → Upper Oven Door Locking System Failure
F11 → Lower Oven Door Locking System Failure
Both involve failure to detect the expected door lock switch condition at the beginning of Self Clean.
Both also use the specified Door Lock Motor checks:
Resistance: 2.6 kΩ
Voltage: 120 VAC
The critical distinction is therefore:
F10 = Upper Oven
F11 = Lower Oven
This distinction should be preserved during diagnosis, particularly on LG appliances with separate upper and lower oven systems.
Can You Clear the F11 Code?
Disconnecting power may reset the electronic control and temporarily remove F11 from the display.
However, resetting the appliance cannot repair a persistent problem with the:
- Door Lock Motor
- Door lock switch
- Lock mechanism
- Wiring
- Electrical connections
- Control circuit
If F11 returns when Self Clean is started, the lower oven locking system should be diagnosed.
Repeated power resets should not be considered a permanent solution.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when F11 repeatedly returns or the lower oven cannot confirm that its door is locked.
A technician may need to:
- Access the lower Door Lock Motor
- Inspect the lock mechanism
- Test the door lock switch
- Measure motor resistance
- Verify the 120 VAC motor supply
- Inspect internal wiring
- Check Main PCB connections
Because diagnosis can involve live 120 VAC measurements, internal electrical testing should only be performed by someone qualified to safely service ovens and ranges.
Key Point
F11 indicates a Lower Oven Door Locking System Failure.
The direct diagnostic information specifies:
Condition: Door lock switch not detected at the beginning of Self Clean
Oven: Lower oven
Connections: Check Main PCB and Door Lock Motor connections
Door Lock Motor resistance: 2.6 kΩ
Door Lock Motor voltage: 120 VAC
F11 does not automatically mean the Door Lock Motor has failed. The motor, lock switch, mechanical locking system, wiring, connections, and control circuit should be evaluated before determining which component requires repair.
F16 — Lower Oven Too Hot
The F16 error code indicates that the lower oven has reached an abnormally high temperature.
The control system monitors oven temperature through the oven temperature sensor. If the lower oven temperature remains above the specified limit for a sufficient period of time during normal operation, the control may stop operation and display F16.
According to LG diagnostic information, F16 is triggered when the lower oven temperature remains above 650°F continuously for more than two minutes, except during Self Clean.
What the F16 Error Code Means
F16 is an over-temperature protection code for the lower oven.
The triggering condition is:
Lower oven temperature above 650°F for more than two continuous minutes.
This temperature condition applies during normal oven operation and specifically excludes Self Clean, because substantially higher temperatures are expected during the cleaning cycle.
The code therefore indicates either that the lower oven has actually become excessively hot or that the temperature-sensing system is reporting an incorrect temperature condition.
Common Causes
Diagnosis of F16 should begin with the lower oven temperature-sensing system.
Possible areas requiring investigation include:
- Lower oven temperature sensor
- Sensor wiring
- Sensor electrical connections
- Incorrect temperature feedback
- Heating system continuing to operate when it should stop
- Electronic control of the heating system
However, the direct F16 source specifically instructs technicians to begin by checking the oven sensor value after the oven has cooled down.
For this reason, the oven sensor should be tested before assuming that a control board or heating component has failed.
What You Can Check
If F16 appears, stop normal oven operation and allow the appliance to cool.
Record useful information such as:
- Whether F16 appeared during Bake, Broil, or another cooking mode
- The temperature setting at the time
- How long the oven had been operating
- Whether food appeared unusually hot or burned
- Whether heating continued after the set temperature was reached
- Whether the displayed temperature appeared abnormal
- Whether F16 returns during another cooking cycle
Remember that the F16 threshold described by the source does not apply to Self Clean operation.
Allow the Oven to Cool Before Testing
LG specifically instructs technicians to measure the oven sensor resistance after cooling down.
This is important because an oven thermistor changes resistance with temperature.
Testing the sensor while the oven is still hot and comparing the result with a room-temperature specification could lead to an incorrect diagnosis.
Allow the lower oven to cool before evaluating the sensor against the specified resistance range.
Check the Oven Temperature Sensor Resistance
The direct F16 diagnostic information provides a specific normal resistance range for the oven sensor:
Approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F.
This gives technicians a useful reference for evaluating the sensor after the oven has cooled.
The expected range can be summarized as:
65°F → approximately 1.06 kΩ
85°F → approximately 1.12 kΩ
The resistance should be evaluated in relation to the actual sensor temperature when the measurement is taken.
What an Abnormal Sensor Reading Can Mean
If the lower oven temperature sensor does not produce a resistance consistent with the specified room-temperature range, the sensor or its circuit requires further diagnosis.
The complete sensor circuit should be considered rather than replacing the sensor solely because F16 appeared.
A technician may need to inspect:
- Sensor itself
- Sensor connector
- Wiring harness
- Terminals
- Continuity between the sensor and electronic control
A poor connection or wiring problem can interfere with the temperature signal reaching the control.
What If the Sensor Tests Normally?
If the oven has cooled and the sensor measurement falls within the expected range, further diagnosis may be necessary to determine why the lower oven reached—or appeared to reach—the F16 over-temperature condition.
At that point, diagnosis may need to consider the rest of the temperature-control system, including how the electronic control manages the lower oven heating components.
The important diagnostic sequence is to verify the temperature sensor first, because this is the check specifically provided for F16.
Actual Overheating vs. Incorrect Temperature Feedback
F16 can be approached by distinguishing between two general conditions.
Actual overheating:
The lower oven is genuinely becoming excessively hot during normal cooking operation.
Incorrect temperature feedback:
The temperature-sensing system is providing information that causes the control to detect an abnormal high-temperature condition.
Observing the oven’s behavior together with measuring the temperature sensor can help distinguish between these possibilities.
If the oven is visibly overheating, continuing to operate it should be avoided until the cause has been identified.
Why Self Clean Is Different
The F16 definition specifically includes an important exception:
Except during Self Clean.
Self Clean intentionally operates the oven at much higher temperatures than ordinary Bake or Broil operation.
Therefore, a temperature that would be abnormal during normal cooking may be expected during the cleaning cycle.
This is why F16 should be interpreted in the context of normal lower oven operation, rather than applying the 650°F threshold to Self Clean.
F16 Diagnostic Sequence
A practical diagnostic sequence is:
F16 displayed
→ Confirm the error involves the lower oven
→ Determine which operating mode was active
→ Verify that the error did not occur as part of normal Self Clean operation
→ Stop operation and allow the oven to cool
→ Measure the lower oven temperature sensor resistance
→ Compare the reading with approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F
→ Inspect the sensor circuit if the reading is abnormal
→ If the sensor circuit tests correctly, investigate the lower oven temperature-control system
This approach follows the direct diagnostic direction while avoiding premature replacement of unrelated components.
Can You Clear the F16 Code?
Disconnecting power may reset the electronic control and temporarily remove F16 from the display.
However, resetting the appliance does not correct the condition that caused the lower oven to exceed—or appear to exceed—the allowed temperature.
If F16 returns during normal cooking, the oven should be diagnosed rather than repeatedly reset.
This is particularly important if the lower oven appears to continue heating beyond the selected temperature.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F16 repeatedly returns
- The lower oven becomes excessively hot
- Food burns despite a normal temperature setting
- Heating appears to continue uncontrollably
- The oven sensor requires testing
- The sensor tests normally but F16 continues
- Internal wiring or heating controls require diagnosis
Because oven heating circuits operate at mains voltage and high temperatures, internal electrical testing should be performed by someone qualified to service ranges and ovens.
Key Point
F16 indicates that the Lower Oven is Too Hot.
The direct diagnostic information specifies:
Trigger: Lower oven temperature remains above 650°F continuously for more than two minutes
Exception: This condition excludes Self Clean
Initial diagnostic step: Allow the oven to cool and check the oven sensor resistance
Normal sensor value: Approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F.
The sensor should therefore be checked before assuming that another component has failed.
F17 — Lower Convection Fan Error
The F17 error code indicates a problem with the lower oven convection fan system in an LG range or oven.
The convection fan circulates heated air throughout the oven cavity to help maintain more even temperatures during convection cooking.
According to LG diagnostic information, F17 appears when convection fan operation cannot be detected for more than one minute.
What the F17 Error Code Means
When a convection cooking mode is operating, the oven control expects the lower convection fan system to respond correctly.
If fan operation cannot be detected for more than one minute, the electronic control may determine that the lower convection fan system is not functioning as expected and display F17.
LG identifies the code as:
Lower Convection Fan Error
with the condition:
Convection fan operation cannot be detected for over 1 minute.
This makes F17 primarily a convection fan system fault, rather than an oven temperature sensor or heating-element error.
Common Causes
The direct F17 diagnostic information specifically directs attention to the connections between the Convection Fan and Main PCB.
Areas that may require inspection include:
- Convection fan harness
- Convection fan electrical connections
- Main PCB connections
- Loose connectors
- Damaged wiring
- Convection fan assembly
- Fan control circuit
Because LG specifically instructs technicians to check the harness first, F17 should not automatically be interpreted as proof that the convection fan motor itself has failed.
What You Can Check
When F17 appears, record how the lower oven behaves.
Useful observations include:
- Whether F17 appears when a convection mode is selected
- Whether the lower convection fan can be heard operating
- Whether the fan starts and then stops
- Whether the error appears approximately after the fan should begin operating
- Whether conventional Bake works differently from convection modes
- Whether F17 returns every time convection cooking is selected
- The complete LG model number
These observations can help determine whether the problem is limited to the convection system or occurs during other oven functions as well.
Check the Convection Fan Harness
LG specifically instructs technicians to:
Check the harness at the Convection Fan and Main PCB.
This should be one of the first internal diagnostic steps.
The harness and connectors should be inspected for conditions such as:
- Loose connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Poor terminal contact
- Bent or backed-out terminal
- Heat-damaged connector
A connection problem can interrupt communication or electrical operation between the Main PCB and convection fan system.
Therefore, the wiring and connections should be checked before replacing the fan or control board.
Check the Main PCB Connection
The Main PCB is part of the convection fan control circuit.
A simplified diagnostic path can be represented as:
Main PCB → Wiring Harness → Lower Convection Fan
If the electrical connection between these components is interrupted, the oven may be unable to detect normal convection fan operation.
The Main PCB connector should therefore be inspected along with the fan-side connection.
A properly seated connector at the fan does not rule out a connection problem at the control board.
Check the Convection Fan
If the harness and connectors are in good condition, the convection fan assembly itself may require further diagnosis.
A technician may need to determine whether:
- The fan attempts to start
- The fan rotates normally
- The fan is mechanically obstructed
- The fan starts intermittently
- The fan motor operates consistently
- The fan receives the appropriate control from the appliance
The direct F17 source does not provide a specific fan motor resistance or voltage specification, so model-specific service information should be used for additional electrical testing.
Electrical vs. Mechanical Fan Problems
A convection fan can fail to operate correctly because of either an electrical problem or a mechanical problem.
Electrical side:
- Wiring harness
- Connectors
- Fan motor circuit
- Main PCB connection
- Fan control system
Mechanical side:
- Fan blade obstruction
- Fan unable to rotate freely
- Mechanical damage to the fan assembly
- Fan motor unable to turn the blade properly
Determining whether the fan is being commanded to operate but cannot physically run can help narrow the diagnostic path.
Why the Convection Fan Matters
The convection fan circulates hot air through the oven cavity during convection cooking.
This airflow helps distribute heat around the food and supports more uniform cooking conditions.
If the lower convection fan cannot operate normally, convection performance may be affected even if other oven components are still capable of producing heat.
For this reason, F17 is more specifically associated with air circulation during convection operation than with the oven’s ability to generate heat.
F17 Diagnostic Sequence
A practical diagnostic sequence for F17 is:
F17 displayed
→ Confirm the error involves the lower oven
→ Determine whether a convection mode was operating
→ Observe whether the convection fan starts
→ Inspect the fan for mechanical obstruction
→ Check the harness at the Convection Fan
→ Check the harness connection at the Main PCB
→ Inspect wiring and terminals
→ If connections are correct, perform model-specific diagnosis of the convection fan and its control circuit
This follows LG’s direct instruction to check the harness while avoiding premature replacement of the fan motor or Main PCB.
F16 vs. F17
Although F16 and F17 are consecutive codes, they represent completely different lower oven systems.
F16 → Lower Oven Too Hot
F17 → Lower Convection Fan Error
F16 directs diagnosis toward an abnormal oven temperature condition and the oven temperature sensor.
F17 directs diagnosis toward the lower convection fan system and the harness between the Convection Fan and Main PCB.
The two codes should therefore have separate diagnostic paths.
Can You Clear the F17 Code?
Disconnecting power may reset the electronic control and temporarily remove F17.
However, a reset cannot correct a persistent:
- Loose harness connection
- Wiring fault
- Fan problem
- Mechanical obstruction
- Fan control problem
If F17 returns when convection operation is attempted, the lower convection fan system should be diagnosed.
Repeated power resets should not be considered a permanent repair.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F17 repeatedly returns
- The lower convection fan does not operate
- The fan starts but stops unexpectedly
- Convection cooking is not working properly
- Internal harness connections require inspection
- The fan or Main PCB circuit requires electrical testing
A technician may need to access internal oven components and perform electrical tests to determine whether the problem is with the fan, wiring, connections, or control system.
Key Point
F17 indicates a Lower Convection Fan Error.
The direct diagnostic information specifies:
Error: Lower Convection Fan Error
Trigger: Convection fan operation cannot be detected for more than 1 minute
Initial diagnostic step: Check the harness at the Convection Fan and Main PCB.
F17 does not by itself prove that the convection fan motor or Main PCB has failed. The harness and connections should be inspected before determining which component requires repair.
F18 — Lower Oven Meat Probe Error
The F18 error code indicates a problem with the lower oven meat probe sensing circuit in an LG range or oven.
The meat probe allows the oven to monitor the internal temperature of food during cooking. When the probe function is being used, the Main PCB expects to receive a valid signal from the Lower Oven Meat Probe Sensor.
If that signal is not detected for more than one minute after cooking begins, the oven may display F18.
What the F18 Error Code Means
F18 is specifically a Lower Oven Meat Probe Error.
The triggering condition is:
No signal reaches the Main PCB from the Lower Oven Meat Probe Sensor for more than one minute after cooking starts.
This makes F18 a meat-probe sensing circuit fault rather than a general oven temperature sensor, heating element, convection fan, or door lock error.
The important diagnostic path is:
Lower Oven Meat Probe Sensor → Meat Probe Sensor Jack / Connections → Main PCB
A problem anywhere along this signal path can prevent the control from detecting the probe correctly.
Common Causes
Based on the direct diagnostic information, the first areas to investigate are:
- Lower Oven Meat Probe Sensor
- Meat Probe Sensor Jack
- Sensor jack connections
- Wiring between the probe circuit and Main PCB
- Main PCB connections
- Loose or damaged connectors
- Poor electrical contact
The F18 code does not automatically prove that the meat probe itself has failed.
LG specifically directs diagnosis toward the connections at both the Main PCB and Lower Oven Meat Probe Sensor Jack.
What You Can Check
If F18 appears, first note the circumstances under which the error occurred.
Useful information includes:
- Whether a meat probe was being used
- Whether F18 appeared shortly after cooking started
- Whether the probe was fully inserted into its jack
- Whether the probe or cable appears damaged
- Whether the probe connection feels loose
- Whether F18 returns when the meat probe function is used again
- Whether other lower oven functions operate normally
Because LG defines F18 by the absence of a probe signal for more than one minute after cooking starts, the timing of the error is useful diagnostic information.
Check the Meat Probe Connection
The meat probe should be properly connected to the lower oven probe jack when the probe cooking function is used.
Before internal diagnosis, check that:
- The probe is fully inserted
- The connector is not obviously damaged
- The probe cable is not visibly damaged
- The probe jack is free of obvious contamination or physical damage
A poor connection at the probe interface can interfere with the temperature signal used by the oven control.
Do not force a damaged or poorly fitting probe connector into the jack.
Check the Lower Oven Meat Probe Sensor Jack
LG specifically identifies the Lower Oven Meat Probe Sensor Jack connections as an area that should be checked.
The sensor jack is important because it forms the electrical interface between the meat probe and the oven’s sensing circuit.
A technician should inspect the relevant connections for conditions such as:
- Loose connection
- Connector not fully seated
- Damaged terminal
- Poor electrical contact
- Damaged wiring
- Heat-related connector damage
- Physical damage to the probe jack
A problem at the jack can interrupt the probe signal even when the meat probe itself is functional.
Check the Main PCB Connections
LG also specifically instructs technicians to check the Main PCB connections.
The Main PCB must receive the probe’s temperature signal in order to monitor food temperature correctly.
A simplified signal path is:
Meat Probe → Lower Oven Meat Probe Sensor Jack → Wiring / Connections → Main PCB
If the signal is interrupted anywhere along this path for more than one minute after cooking starts, F18 may be triggered.
For this reason, both ends of the circuit should be inspected before concluding that a component needs replacement.
Probe vs. Wiring vs. Control Diagnosis
F18 should be treated as a signal-path problem first.
A practical diagnostic approach is to determine whether the Main PCB is failing to receive the probe signal because of:
Probe side
→ Problem with the meat probe or its connection
Connection side
→ Problem at the Lower Oven Meat Probe Sensor Jack
Wiring side
→ Interrupted or poor electrical connection between the jack and control
Control side
→ Main PCB connection or related control issue
This approach helps avoid replacing the meat probe or Main PCB without first checking the connections specifically identified in the diagnostic information.
No Resistance Specification Is Provided for F18
The direct F18 diagnostic page does not provide a specific resistance or voltage value for testing the Lower Oven Meat Probe Sensor.
Therefore, a resistance specification from another oven sensor or another error code should not be applied to F18.
If electrical testing beyond connection inspection is necessary, technicians should use the service information for the specific LG model.
This is particularly important because a meat probe sensor should not automatically be treated as electrically identical to the oven cavity temperature sensor.
Why the Meat Probe Signal Matters
The meat probe is designed to measure the internal temperature of food and provide that information to the oven’s electronic control.
The control can use this temperature information during probe-assisted cooking.
If the Main PCB cannot detect the probe signal, it cannot reliably determine the food’s internal temperature.
F18 therefore protects against continuing probe-controlled operation without valid temperature feedback.
F18 Diagnostic Sequence
A practical diagnostic sequence is:
F18 displayed
→ Confirm the error involves the lower oven
→ Determine whether the meat probe function was being used
→ Check that the probe is properly inserted
→ Inspect the probe and cable for visible damage
→ Inspect the Lower Oven Meat Probe Sensor Jack
→ Check the sensor jack connections
→ Check Main PCB connections
→ Inspect the wiring between the probe circuit and Main PCB
→ If connections are correct, continue with model-specific probe and control diagnosis
This sequence follows the direct LG troubleshooting direction without assuming that the probe or Main PCB has failed.
F17 vs. F18
Although F17 and F18 are consecutive lower oven codes, they identify different systems.
F17 → Lower Convection Fan Error
F18 → Lower Oven Meat Probe Error
F17 is triggered when convection fan operation cannot be detected for more than one minute.
F18 is triggered when the Main PCB receives no signal from the Lower Oven Meat Probe Sensor for more than one minute after cooking starts.
The similar timing should not cause the two codes to be confused—the affected components and diagnostic paths are completely different.
Can You Clear the F18 Code?
Power cycling the appliance may reset the electronic control and temporarily remove F18.
However, a reset cannot repair a persistent problem involving:
- Meat probe connection
- Meat Probe Sensor Jack
- Internal wiring
- Electrical connectors
- Main PCB connection
If F18 returns when the meat probe function is used, the probe sensing circuit should be diagnosed.
Repeatedly resetting the oven is not a permanent repair for a recurring probe signal problem.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F18 repeatedly returns
- The meat probe is not detected
- The probe connection appears damaged
- The Meat Probe Sensor Jack requires inspection
- Internal wiring requires testing
- Main PCB connections need to be checked
- The external probe appears normal but the error continues
Further diagnosis may require access to internal oven wiring and model-specific electrical testing.
Key Point
F18 indicates a Lower Oven Meat Probe Error.
The direct diagnostic information specifies:
Error: Lower Oven Meat Probe Error
Trigger: No signal to the Main PCB from the Lower Oven Meat Probe Sensor for more than one minute after cooking starts
Initial checks: Check Main PCB connections and Lower Oven Meat Probe Sensor Jack connections.
F18 does not automatically mean that the meat probe or Main PCB needs replacement. The probe connection, sensor jack, wiring, and Main PCB connections should be evaluated first.
F19 — Lower Oven Temperature Sensor Error
The F19 error code indicates a problem with the lower oven temperature sensor circuit in an LG range or oven.
The electronic control relies on the lower oven temperature sensor to monitor the temperature inside the oven cavity. If the Main PCB detects an abnormal sensor resistance value, it may display F19.
The diagnostic process should focus on the lower oven sensor, its wiring and connections, and the signal reaching the Main PCB.
What the F19 Error Code Means
The lower oven temperature sensor is a thermistor whose resistance changes as its temperature changes.
The Main PCB monitors this resistance to determine the temperature inside the lower oven.
F19 indicates that the control has detected a sensor value outside the expected operating condition.
This can occur because of a problem with the sensor itself or because the sensor signal is being affected somewhere in the electrical circuit between the sensor and Main PCB.
For this reason, F19 should be treated as a lower oven temperature sensing circuit error, not automatically as proof that the sensor itself must be replaced.
Common Causes
Possible areas requiring inspection include:
- Lower oven temperature sensor
- Sensor wiring
- Sensor connector
- Loose electrical connection
- Damaged wiring
- Open sensor circuit
- Shorted sensor circuit
- Poor terminal contact
- Main PCB connection
The temperature sensor should be electrically tested before replacing parts.
What You Can Check
If F19 appears, record how the lower oven behaves.
Useful observations include:
- Whether F19 appears immediately after power-up
- Whether it appears when the lower oven begins heating
- Whether the displayed temperature appears abnormal
- Whether the lower oven heats normally
- Whether heating stops when F19 appears
- Whether the error occurs repeatedly
- Whether F19 returns after the oven has cooled
- The complete LG model number
These observations can help determine whether the problem is intermittent or consistently associated with the lower oven temperature sensor circuit.
Allow the Oven to Cool Before Testing
The resistance of an oven thermistor changes with temperature.
For that reason, the sensor should be allowed to cool before its resistance is compared with a room-temperature specification.
Testing a hot sensor and comparing the result directly with a value specified at approximately room temperature can lead to an incorrect diagnosis.
Once the lower oven has cooled, the sensor can be checked against the resistance range provided in the diagnostic information.
Check the Lower Oven Sensor Resistance
The direct F19 diagnostic information provides a specific resistance range for the oven temperature sensor:
Approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F. (lgerrorcodes.com)
The reference range can be summarized as:
65°F → approximately 1.06 kΩ
85°F → approximately 1.12 kΩ
The actual resistance measurement should be interpreted in relation to the temperature of the sensor when it is tested.
A reading significantly outside the expected range can indicate a problem with the sensor or its circuit.
Check the Sensor Wiring and Connections
The temperature sensor is only one part of the complete sensing circuit.
The signal path can be represented as:
Lower Oven Temperature Sensor → Connector / Wiring Harness → Main PCB
A problem anywhere along this path can cause the Main PCB to detect an abnormal sensor value.
Inspect the circuit for:
- Loose connectors
- Damaged wires
- Broken conductors
- Poor terminal contact
- Bent or backed-out terminals
- Heat-damaged connections
- Open or shorted wiring
Connections should be checked before assuming that either the sensor or Main PCB is defective.
Sensor vs. Wiring Diagnosis
If the sensor resistance is outside the expected range when measured correctly at room temperature, the sensor itself becomes a likely source of the F19 condition.
If the sensor tests normally, the diagnostic process should continue through the wiring and connections between the sensor and Main PCB.
This distinction is important because a good temperature sensor cannot provide reliable temperature information if its signal cannot reach the electronic control correctly.
Testing the sensor directly can also help separate a sensor fault from a harness or connector problem.
What If the Sensor Tests Normally?
If the lower oven temperature sensor measures within the expected range, F19 should not immediately be treated as proof that a new sensor is required.
Further diagnosis may include:
- Checking sensor connectors
- Inspecting the wiring harness
- Checking continuity through the sensor circuit
- Inspecting Main PCB connections
- Looking for an intermittent connection
- Using model-specific service information to continue diagnosis
Only after the sensor and its signal path have been verified should the electronic control become a stronger diagnostic consideration.
F16 vs. F19
F16 and F19 both involve lower oven temperature, but they describe different fault conditions.
F16 — Lower Oven Too Hot
→ The lower oven remains above 650°F for more than two continuous minutes, except during Self Clean.
F19 — Lower Oven Temperature Sensor Error
→ The control detects an abnormal condition in the lower oven temperature sensor circuit.
Both codes may involve checking the oven sensor, and both use the room-temperature reference of approximately:
1.06 kΩ at 65°F – 1.12 kΩ at 85°F
However, the reason for testing the sensor is different.
F16 begins with an over-temperature condition.
F19 begins with an abnormal temperature sensor signal.
Why Accurate Temperature Feedback Matters
The Main PCB depends on the lower oven temperature sensor to determine how hot the oven cavity is.
That information is used to control heating during normal operation.
If the sensor signal becomes unreliable, the electronic control may no longer be able to accurately determine the lower oven temperature.
F19 therefore identifies a fault in a critical temperature-feedback system and should not simply be ignored if the code repeatedly returns.
F19 Diagnostic Sequence
A practical diagnostic sequence is:
F19 displayed
→ Confirm the error involves the lower oven
→ Allow the oven to cool
→ Inspect the temperature sensor and connector
→ Measure sensor resistance
→ Compare with approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F
→ If abnormal, investigate the sensor
→ If normal, inspect wiring and connectors
→ Check the signal path to the Main PCB
→ Continue with model-specific control diagnosis if the complete sensor circuit tests correctly
This approach helps distinguish a defective sensor from a wiring, connector, or control-side problem.
Can You Clear the F19 Code?
Disconnecting power may reset the electronic control and temporarily remove F19 from the display.
However, a reset cannot repair:
- An abnormal temperature sensor
- Open or shorted sensor wiring
- Loose electrical connection
- Damaged connector
- Persistent sensor circuit problem
If F19 returns, the lower oven temperature sensing circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F19 repeatedly returns
- The lower oven does not heat correctly
- Temperature readings appear abnormal
- The sensor requires resistance testing
- Internal wiring requires inspection
- The sensor tests normally but F19 continues
A technician can isolate the sensor from the rest of the circuit, verify its resistance, inspect the harness, and determine whether the fault originates at the sensor, wiring, connections, or electronic control.
Key Point
F19 indicates a Lower Oven Temperature Sensor Error.
The lower oven temperature sensor should be checked after the appliance has cooled.
The direct diagnostic information provides a normal sensor resistance of approximately:
1.06 kΩ at 65°F to 1.12 kΩ at 85°F. (lgerrorcodes.com)
If the sensor tests correctly, the wiring, connectors, and signal path to the Main PCB should be investigated before replacing additional components.
F2 — Lower Oven Temperature Sensor Error
The F2 error code indicates a problem with the lower oven temperature sensor circuit in an LG range or oven.
The Main PCB relies on the Lower Oven Sensor to provide accurate temperature information from inside the oven cavity. If the control does not receive the expected sensor signal, it may display the F2 error code.
Diagnosis should focus on the Lower Oven Sensor, its electrical connections, wiring, and the signal path to the Main PCB.
What the F2 Error Code Means
The Lower Oven Sensor is a temperature-sensitive component used by the electronic control to monitor oven cavity temperature.
As the oven temperature changes, the sensor’s resistance changes. The Main PCB uses this information to determine the actual oven temperature and regulate heating operation.
F2 indicates that the control is not receiving the expected information from the Lower Oven Sensor.
This makes F2 primarily a lower oven temperature sensing circuit fault, rather than a heating element, convection fan, or door lock error.
Common Causes
The F2 diagnostic path should focus on components and connections associated with the Lower Oven Sensor, including:
- Lower Oven Sensor
- Sensor connector
- Sensor wiring
- Loose electrical connections
- Damaged wiring
- Poor terminal contact
- Main PCB connections
- Temperature sensor signal circuit
F2 does not automatically mean that the Lower Oven Sensor itself has failed.
A wiring or connection problem can interrupt the sensor signal even when the sensor is still functioning correctly.
What You Can Check
If F2 appears, record how the lower oven behaves.
Useful observations include:
- Whether F2 appears immediately after power-up
- Whether it appears when the lower oven begins heating
- Whether the lower oven reaches the selected temperature
- Whether the displayed temperature behaves abnormally
- Whether heating stops when F2 appears
- Whether F2 returns after the appliance is restarted
- The complete LG model number
These details can help determine whether the sensor fault is constant or intermittent.
Check the Lower Oven Sensor Connections
The direct F2 diagnostic information directs technicians to check the Lower Oven Sensor connections.
Inspect the sensor circuit for conditions such as:
- Loose connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Bent or backed-out terminal
- Poor electrical contact
- Heat-damaged connector
A poor connection can prevent the Main PCB from receiving accurate temperature information.
Connections should therefore be inspected before replacing the sensor.
Check the Main PCB Connections
The Main PCB connections should also be checked.
The temperature signal follows a path similar to:
Lower Oven Sensor → Wiring / Connectors → Main PCB
An interruption anywhere along this path can cause the control to lose the expected sensor signal.
This means a properly functioning sensor can still result in F2 if its electrical signal cannot reliably reach the Main PCB.
Check the Lower Oven Sensor Resistance
The direct diagnostic information provides a room-temperature resistance specification for the Lower Oven Sensor.
After the oven has cooled, the sensor should measure approximately:
1.06 kΩ at 65°F to 1.12 kΩ at 85°F
This can be summarized as:
65°F → approximately 1.06 kΩ
85°F → approximately 1.12 kΩ
Because thermistor resistance changes with temperature, the measurement should be interpreted according to the actual sensor temperature.
Why the Oven Should Be Cool Before Testing
The Lower Oven Sensor is temperature-sensitive, so its resistance naturally changes as the oven heats and cools.
The 1.06–1.12 kΩ specification applies around room temperature.
Testing a hot sensor and comparing its resistance directly with a room-temperature specification could produce an incorrect diagnosis.
For an accurate comparison, allow the oven to cool before measuring the sensor.
Sensor vs. Wiring Diagnosis
The sensor can be tested separately from the rest of the circuit to help determine where the problem originates.
If the Lower Oven Sensor measures outside the expected resistance range at the appropriate temperature, the sensor itself becomes a likely source of the fault.
If the sensor measures correctly, diagnosis should continue through:
- Sensor connector
- Wiring harness
- Electrical terminals
- Main PCB connector
- Complete sensor signal path
This helps avoid replacing a good sensor when the actual problem is a damaged wire or poor connection.
What If the Sensor Tests Normally?
If the Lower Oven Sensor measures approximately 1.06–1.12 kΩ at 65–85°F, further diagnosis should focus on the circuit between the sensor and electronic control.
A technician may need to:
- Check wiring continuity
- Inspect connectors
- Look for intermittent connections
- Verify terminal contact
- Check Main PCB connections
- Continue with model-specific control diagnosis
The Main PCB should not automatically be replaced simply because F2 appears.
The sensor and its signal path should be verified first.
F2 vs. F19
F2 and F19 are both associated with the lower oven temperature sensing system, so they can appear very similar from a troubleshooting perspective.
Both direct diagnostic procedures point toward checking the Lower Oven Sensor circuit, and the sensor reference is approximately:
1.06 kΩ at 65°F – 1.12 kΩ at 85°F
However, each code should still remain a separate entry because LG identifies them separately in its diagnostic system.
When either code appears, the exact appliance model number should be considered before assuming that the codes are interchangeable.
Why Accurate Temperature Feedback Matters
The Main PCB depends on the Lower Oven Sensor to regulate cooking temperature.
If the temperature signal is missing or unreliable, the control may not be able to accurately determine the actual temperature inside the oven cavity.
This can interfere with normal heating control and cooking performance.
For this reason, a recurring F2 error should be diagnosed rather than repeatedly cleared.
F2 Diagnostic Sequence
A practical diagnostic sequence is:
F2 displayed
→ Confirm the problem involves the lower oven
→ Allow the oven to cool
→ Inspect Lower Oven Sensor connections
→ Inspect Main PCB connections
→ Measure Lower Oven Sensor resistance
→ Compare with approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F
→ If the sensor is abnormal, investigate the sensor
→ If the sensor is normal, inspect wiring and connectors
→ Continue with model-specific control diagnosis if the complete sensor circuit tests correctly
This approach helps distinguish between a sensor fault and a problem elsewhere in the sensing circuit.
Can You Clear the F2 Code?
Disconnecting and restoring power may reset the electronic control and temporarily remove F2.
However, a reset cannot repair:
- Defective temperature sensor
- Loose sensor connection
- Damaged wiring
- Poor electrical contact
- Persistent sensor circuit problem
If F2 returns, the Lower Oven Sensor circuit should be diagnosed.
Repeated power cycling should not be considered a permanent repair.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F2 repeatedly returns
- The lower oven does not heat correctly
- Oven temperature appears inaccurate
- The Lower Oven Sensor requires testing
- Internal wiring requires inspection
- The sensor tests normally but the error continues
A technician can isolate the sensor, verify its resistance, inspect the wiring and connections, and determine whether the problem originates with the sensor, harness, or electronic control.
Key Point
F2 indicates a Lower Oven Temperature Sensor Error.
The primary diagnostic path is:
Lower Oven Sensor → Connections / Wiring → Main PCB
Check the connections at both the Lower Oven Sensor and Main PCB, and verify the temperature sensor after the oven has cooled.
The expected sensor resistance is approximately:
1.06 kΩ at 65°F to 1.12 kΩ at 85°F.
A normal sensor reading means the wiring, connectors, and remaining signal path should be investigated before replacing additional components.
F20 — Lower Oven Door Locking System Failure
The F20 error code indicates a door locking system failure in the lower oven of an LG range or oven.
The lower oven uses a door locking mechanism during the Self Clean cycle. When Self Clean begins, the electronic control expects the locking system to move into the required position and provide confirmation through the door lock switch.
If the expected door lock switch condition is not detected, the appliance may stop the cleaning sequence and display F20.
What the F20 Error Code Means
F20 occurs when the lower oven door lock switch is not detected at the beginning of Self Clean.
During the cleaning cycle, the oven operates at temperatures significantly higher than those used during normal cooking. The electronic control therefore needs confirmation that the door locking system is operating correctly before Self Clean can proceed.
The direct diagnostic information identifies F20 as:
Door Locking System Failure (Lower Oven)
with the cause:
Door lock switch not detected at the beginning of Self Clean.
This makes F20 specifically a lower oven door locking system fault, rather than a temperature sensor or heating-system error.
Common Causes
Diagnosis should focus on the lower oven door locking circuit and mechanism, including:
- Door Lock Motor
- Door lock switch
- Door Lock Motor connections
- Main PCB connections
- Wiring between the Main PCB and lock assembly
- Loose or damaged connectors
- Mechanical problems with the locking mechanism
F20 does not automatically mean that the Door Lock Motor has failed.
Because the defining condition is that the control cannot detect the expected lock switch state, the motor, switch, wiring, connections, and mechanical mechanism should all be considered.
What You Can Check
If F20 appears, note exactly what happens when Self Clean is selected.
Useful observations include:
- Whether the lower oven door attempts to lock
- Whether the Door Lock Motor can be heard operating
- Whether the locking mechanism moves
- Whether the door actually reaches the locked position
- Whether the lock indicator changes
- Whether F20 appears immediately after starting Self Clean
- Whether F20 occurs every time Self Clean is selected
These observations can help distinguish between a motor that does not operate and a mechanism that moves but fails to provide the expected lock confirmation.
Check the Main PCB Connections
The direct F20 diagnostic procedure specifically instructs technicians to check the Main PCB connections.
The Main PCB is responsible for controlling and monitoring the lower oven locking sequence.
A simplified operating path is:
Main PCB → Door Lock Motor / Lock Mechanism → Door Lock Switch → Main PCB
If a connector is loose or the circuit is interrupted, the control may be unable to operate the lock or recognize that the door has reached the locked position.
The Main PCB connections should therefore be inspected before assuming that the control board itself is defective.
Check the Door Lock Motor Connections
LG also specifically directs technicians to check the Door Lock Motor connections.
Inspect the relevant connectors and wiring for:
- Loose connections
- Connectors not fully seated
- Damaged wiring
- Broken conductors
- Bent or backed-out terminals
- Poor electrical contact
- Heat-damaged connectors
A poor connection can prevent the motor from receiving power even when the motor itself is functional.
Connections should therefore be verified before replacing the Door Lock Motor.
Check the Door Lock Motor Resistance
The direct F20 diagnostic information provides a specific resistance value for the Door Lock Motor:
2.6 kΩ
A qualified technician can measure the motor winding and compare the result with this specification.
If the measured resistance is substantially inconsistent with the specified value, the Door Lock Motor may require further evaluation.
Resistance testing should be performed with electrical power disconnected from the appliance.
Check for 120 VAC
LG also specifies:
120 VAC
as part of the Door Lock Motor diagnostic procedure.
Checking the voltage at the appropriate point can help distinguish between a motor problem and a control or wiring problem.
The basic diagnostic logic is:
120 VAC present + Door Lock Motor does not operate correctly
→ Investigate the Door Lock Motor and mechanical locking system.
120 VAC missing when the motor should be operating
→ Investigate wiring, connectors, Main PCB connections, and the control side of the circuit.
Because this test involves live mains voltage, it should only be performed by someone qualified to safely diagnose energized appliances.
Check the Door Lock Switch
The condition that triggers F20 is specifically related to the door lock switch not being detected.
This means diagnosis should not focus exclusively on whether the Door Lock Motor turns.
The locking mechanism must also reach the correct position and provide the expected switch feedback to the electronic control.
A problem may occur if:
- The lock does not reach its intended position
- The switch does not change state
- The mechanism does not properly activate the switch
- The switch circuit has a poor connection
- The switch signal cannot reach the Main PCB
Therefore, a motor that appears to operate does not necessarily rule out an F20 fault.
Electrical vs. Mechanical Lock Failure
The lower oven locking system contains both electrical and mechanical components.
Electrical side:
- Door Lock Motor
- Door lock switch
- 120 VAC motor supply
- Wiring harness
- Connectors
- Main PCB connections
Mechanical side:
- Lock mechanism
- Door latch movement
- Mechanical obstruction
- Misalignment
- Mechanism failing to reach the switch position
A complete diagnosis should determine whether the locking mechanism cannot move or whether it moves but the expected locked-position confirmation is never received.
F20 Diagnostic Sequence
A practical diagnostic sequence is:
F20 appears at the beginning of Self Clean
→ Confirm the error involves the lower oven
→ Observe whether the door attempts to lock
→ Inspect the mechanical lock assembly
→ Check Main PCB connections
→ Check Door Lock Motor connections
→ Inspect the door lock switch circuit
→ Measure Door Lock Motor resistance: 2.6 kΩ
→ Verify 120 VAC during the appropriate operating condition
→ Determine whether the problem originates with the motor, switch, mechanism, wiring, or control circuit
This approach avoids replacing the Door Lock Motor solely because F20 appears.
F20 vs. F11
The direct source describes F20 and F11 very similarly.
F11 → Lower Oven Door Locking System Failure
F20 → Lower Oven Door Locking System Failure
For both codes, the provided diagnostic information includes:
- Door lock switch not detected at the beginning of Self Clean
- Check Main PCB connections
- Check Door Lock Motor connections
- Door Lock Motor: 2.6 kΩ
- Door Lock Motor: 120 VAC
Because LG lists these as separate error codes, they should remain separate entries in the error-code guide even though their published diagnostic paths overlap.
The complete model number should be used when determining which code and service procedure apply to a particular appliance.
Can You Clear the F20 Code?
Disconnecting and restoring power may reset the electronic control and temporarily remove F20.
However, a reset cannot repair a persistent problem with the:
- Door Lock Motor
- Door lock switch
- Mechanical lock assembly
- Wiring
- Electrical connections
- Control circuit
If F20 returns when Self Clean is started, the lower oven door locking system should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F20 repeatedly returns
- The lower oven cannot enter Self Clean
- The door does not lock
- The locking mechanism operates abnormally
- Door Lock Motor resistance needs to be measured
- The 120 VAC supply requires testing
- Internal wiring or Main PCB connections require diagnosis
Live-voltage testing should only be performed by someone qualified to safely service ovens and ranges.
Key Point
F20 indicates a Lower Oven Door Locking System Failure.
The direct diagnostic information specifies:
Condition: Door lock switch not detected at the beginning of Self Clean
Connections: Check Main PCB and Door Lock Motor connections
Door Lock Motor resistance: 2.6 kΩ
Door Lock Motor voltage: 120 VAC
The code does not automatically prove that the Door Lock Motor itself has failed. The lock switch, motor, wiring, connections, mechanical lock assembly, and control circuit should be evaluated.
F21 — Right Steam Sensor Open / Steam Sensor Failure
The F21 error code indicates a problem with the right steam temperature sensor circuit in an LG range or oven.
The steam system uses a thermistor to provide temperature information to the electronic control. If the control detects an open or shorted circuit condition in the steam thermistor circuit, it may display F21.
LG specifically identifies F21 as:
Right Steam Sensor Open
and categorizes the condition as a Steam Sensor Failure.
What the F21 Error Code Means
The steam thermistor is a temperature-sensitive component used by the appliance’s electronic control system to monitor temperature within the steam system.
Its electrical resistance changes with temperature, allowing the Main PCB to interpret temperature conditions.
For F21, the control has detected an abnormal electrical condition associated with this sensor circuit.
The direct diagnostic information describes the cause as an:
Open or shorted circuit condition of the steam thermistor.
This means diagnosis should focus on the steam thermistor and its complete electrical path to the Main PCB, rather than assuming another oven component has failed.
Common Causes
Areas that should be considered during F21 diagnosis include:
- Right steam thermistor
- Open thermistor circuit
- Shorted thermistor circuit
- Steam thermistor connector
- Wiring between the thermistor and Main PCB
- Loose electrical connection
- Damaged wiring
- Poor terminal contact
- Main PCB connection
Because a wiring or connection problem can produce an open or shorted circuit condition, F21 does not automatically prove that the thermistor itself needs replacement.
What You Can Check
If F21 appears, record when and how the error occurs.
Useful information includes:
- Whether F21 appears when a steam-related function is selected
- Whether the error appears immediately or after operation begins
- Whether other oven functions operate normally
- Whether F21 returns after restarting the appliance
- Whether any recent service work was performed
- The complete LG model number
The model number is useful because steam-system configuration can vary between LG appliances.
Check the Steam Thermistor Connections
LG specifically instructs technicians to check the steam thermistor connections.
Inspect the thermistor circuit for:
- Loose connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Shorted wires
- Bent or backed-out terminal
- Poor electrical contact
- Heat-damaged connection
A connection problem can prevent the Main PCB from receiving the expected thermistor signal even when the sensor itself is functional.
Check the Main PCB Connections
The direct F21 troubleshooting information also specifies checking the Main PCB connections.
The basic sensor signal path can be represented as:
Right Steam Thermistor → Wiring / Connectors → Main PCB
An open or shorted condition anywhere along this path may interfere with the temperature signal.
Both the sensor-side and control-side connections should therefore be checked before determining which component requires repair.
Check the Steam Thermistor Resistance
LG provides a specific resistance specification for the steam thermistor:
1.09 kΩ at 77°F.
This provides an important reference point for diagnosing F21.
At approximately:
77°F → Steam thermistor ≈ 1.09 kΩ
The thermistor should be tested at or near the specified temperature for a meaningful comparison.
Because thermistor resistance changes with temperature, a measurement taken at a significantly different temperature should not be expected to match the 77°F reference exactly.
Open vs. Shorted Thermistor Circuit
The direct F21 source specifically mentions both open and shorted circuit conditions.
An open circuit means the electrical path through the sensor circuit has been interrupted.
Possible areas include:
- Failed thermistor
- Disconnected connector
- Broken wire
- Poor terminal connection
A shorted circuit indicates an unintended low-resistance electrical path in the thermistor circuit.
Possible areas requiring inspection include:
- Thermistor
- Damaged wiring
- Connector
- Terminals
Electrical testing helps distinguish between these conditions.
Sensor vs. Wiring Diagnosis
A practical way to isolate F21 is to test the steam thermistor and then evaluate the rest of the circuit.
If the thermistor does not correspond to the specified 1.09 kΩ at 77°F, the sensor requires further evaluation.
If the thermistor itself tests correctly, diagnosis should continue through:
- Thermistor connector
- Wiring harness
- Electrical terminals
- Main PCB connector
- Complete sensor circuit
This helps avoid replacing a functioning thermistor when the actual fault is an open wire or poor connection.
What If the Thermistor Tests Normally?
If the right steam thermistor measures approximately 1.09 kΩ at 77°F, the sensor itself may not be the source of the problem.
Further diagnosis should focus on the electrical path between the thermistor and Main PCB.
A technician may need to check:
- Wiring continuity
- Connector condition
- Terminal contact
- Intermittent open circuits
- Shorted wiring
- Main PCB connections
Model-specific service information should be used if diagnosis needs to proceed beyond these checks.
F21 vs. Lower Oven Temperature Sensor Codes
F21 should not be confused with codes such as F2 or F19.
F2 / F19
→ Lower oven temperature sensor system
F21
→ Right steam sensor / steam thermistor circuit
The sensor specifications are also different.
For F21, the direct source provides:
Steam thermistor: 1.09 kΩ at 77°F
Therefore, resistance specifications from the lower oven temperature sensor should not automatically be applied to the F21 steam sensor.
F21 Diagnostic Sequence
A practical diagnostic sequence is:
F21 displayed
→ Confirm the code and appliance model
→ Inspect the right steam thermistor connection
→ Inspect Main PCB connections
→ Check wiring for an open or shorted condition
→ Measure steam thermistor resistance
→ Compare with approximately 1.09 kΩ at 77°F
→ If resistance is abnormal, investigate the thermistor
→ If resistance is correct, continue diagnosing wiring and connections
→ Use model-specific service information if the complete sensor circuit tests correctly
This follows the direct diagnostic information while avoiding unnecessary parts replacement.
Can You Clear the F21 Code?
Disconnecting and restoring power may reset the electronic control and temporarily remove F21.
However, a reset cannot repair:
- Open thermistor circuit
- Shorted thermistor circuit
- Defective thermistor
- Broken wiring
- Loose connection
- Persistent Main PCB connection problem
If F21 returns, the steam sensor circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F21 repeatedly returns
- Steam functions do not operate correctly
- The steam thermistor requires resistance testing
- Internal wiring requires inspection
- An open or shorted circuit needs to be located
- The thermistor tests correctly but F21 continues
A technician can isolate the thermistor, measure its resistance, check wiring continuity, inspect connectors, and determine where the sensor signal is being interrupted.
Key Point
F21 indicates a Steam Sensor Failure and is specifically identified as Right Steam Sensor Open.
The direct diagnostic information specifies:
Cause: Open or shorted circuit condition of the steam thermistor
F21: Right Steam Sensor Open
Initial checks: Main PCB connections and steam thermistor connections
Thermistor resistance: 1.09 kΩ at 77°F.
F21 does not automatically mean the steam thermistor itself has failed. The thermistor, wiring, connectors, and Main PCB connections should be checked as part of the complete sensor circuit.
F22 — Left Steam Sensor Open / Steam Sensor Failure
The F22 error code indicates a problem with the left steam temperature sensor circuit in an LG range or oven.
The steam system uses a thermistor to provide temperature information to the electronic control. If an open or shorted circuit condition is detected in the steam thermistor circuit, the appliance may display F22.
For this code, the affected circuit is specifically the Left Steam Sensor.
What the F22 Error Code Means
LG identifies F22 as:
Left Steam Sensor Open
under the broader diagnostic condition:
Steam Sensor Failure
The steam thermistor is a temperature-sensitive component whose electrical resistance changes with temperature. The electronic control uses this signal to monitor conditions within the steam system.
If the expected sensor signal is interrupted or electrically abnormal, the Main PCB may detect the fault and generate F22.
Common Causes
The direct diagnostic information identifies an open or shorted circuit condition of the steam thermistor.
Areas that may require inspection include:
- Left steam thermistor
- Open thermistor circuit
- Shorted thermistor circuit
- Thermistor connector
- Wiring between the thermistor and Main PCB
- Loose electrical connection
- Damaged wiring
- Poor terminal contact
- Main PCB connection
F22 does not automatically mean that the steam thermistor itself must be replaced.
A broken wire, loose connector, or another circuit problem can also prevent the Main PCB from receiving the expected sensor signal.
What You Can Check
If F22 appears, record the circumstances surrounding the error.
Useful information includes:
- Whether a steam-related cooking function was being used
- Whether F22 appears immediately or after operation begins
- Whether the error returns consistently
- Whether other oven functions operate normally
- Whether the appliance was recently serviced
- Whether wiring or connectors were recently disturbed
- The complete LG model number
These details can help determine whether the problem is isolated to the steam sensor system.
Check the Left Steam Thermistor Connections
The steam thermistor connections should be inspected as part of the F22 diagnostic process.
Look for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Poor electrical contact
- Heat-damaged connection
Because the fault can be caused by an open circuit, even a single disconnected or damaged conductor can prevent the Main PCB from receiving the expected sensor information.
Check the Main PCB Connections
The Main PCB connections should also be checked.
The basic signal path is:
Left Steam Thermistor → Wiring / Connectors → Main PCB
A problem anywhere along this path can cause the sensor circuit to appear open or shorted to the control.
Both ends of the circuit should therefore be inspected before replacing the thermistor or electronic control.
Check the Steam Thermistor Resistance
The direct diagnostic information provides a specific resistance reference for the steam thermistor:
1.09 kΩ at 77°F
This provides a useful reference point when evaluating the sensor.
At approximately:
77°F → Steam Thermistor ≈ 1.09 kΩ
Because a thermistor changes resistance with temperature, the sensor should be near the specified temperature when comparing the measurement directly with this value.
Open Circuit Condition
An open circuit means the electrical path through the steam sensor circuit has been interrupted.
Possible causes can include:
- Open thermistor
- Broken wire
- Disconnected connector
- Poor terminal contact
- Damaged connection
If the circuit is open, the Main PCB cannot receive the expected temperature-dependent resistance signal from the left steam thermistor.
Shorted Circuit Condition
The F22 diagnostic information also identifies a shorted circuit condition as a possible cause.
This can involve:
- Shorted thermistor
- Damaged wiring
- Conductors contacting incorrectly
- Connector or terminal problem
Electrical testing can help determine whether the circuit is open, shorted, or producing a resistance value consistent with the expected sensor specification.
Sensor vs. Wiring Diagnosis
A useful diagnostic approach is to evaluate the steam thermistor separately from the wiring whenever possible.
If the thermistor does not correspond to approximately 1.09 kΩ at 77°F, the sensor itself requires further investigation.
If the thermistor tests normally, diagnosis should continue through:
- Thermistor connector
- Wiring harness
- Electrical terminals
- Main PCB connector
- Complete sensor signal path
This prevents unnecessary replacement of a functional sensor when the actual fault is a damaged wire or poor connection.
What If the Thermistor Tests Normally?
A normal thermistor reading does not automatically rule out F22.
If the sensor measures approximately 1.09 kΩ at 77°F, inspect the remaining circuit for:
- Wiring continuity problems
- Intermittent open circuit
- Shorted wiring
- Loose connectors
- Poor terminal contact
- Main PCB connection problems
If the entire external sensor circuit tests correctly, model-specific service information should be used for further control-side diagnosis.
F21 vs. F22
F21 and F22 are closely related steam sensor codes.
F21 → Right Steam Sensor Open
F22 → Left Steam Sensor Open
Both belong to the Steam Sensor Failure category.
Both direct diagnosis toward an open or shorted steam thermistor circuit.
Both use the same thermistor reference:
1.09 kΩ at 77°F
The critical distinction is therefore which steam sensor circuit is affected:
F21 = Right
F22 = Left
The correct sensor circuit should be identified before testing or replacing components.
F22 vs. Oven Temperature Sensor Codes
F22 should not be confused with lower oven temperature sensor codes such as F2 or F19.
Those codes involve the sensor used to monitor the temperature of the oven cavity.
F22 specifically involves the left steam thermistor circuit.
The relevant sensor specification is also different:
F22 steam thermistor → 1.09 kΩ at 77°F
Sensor specifications from other oven error codes should not automatically be applied to the F22 steam sensor.
F22 Diagnostic Sequence
A practical diagnostic sequence is:
F22 displayed
→ Confirm the appliance model
→ Identify the Left Steam Sensor circuit
→ Inspect the steam thermistor connection
→ Inspect Main PCB connections
→ Check wiring for open or shorted conditions
→ Measure the steam thermistor resistance
→ Compare with approximately 1.09 kΩ at 77°F
→ If abnormal, investigate the thermistor
→ If normal, continue through wiring and connectors
→ Use model-specific service information if the complete circuit tests correctly
This approach follows the published diagnostic direction while avoiding unnecessary component replacement.
Can You Clear the F22 Code?
Disconnecting and restoring power may temporarily clear F22 from the display.
However, a reset cannot repair:
- Open steam thermistor
- Shorted thermistor
- Broken wiring
- Loose connector
- Damaged terminal
- Persistent sensor circuit problem
If F22 returns, the left steam sensor circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F22 repeatedly returns
- Steam functions do not operate correctly
- The thermistor requires resistance testing
- Internal wiring requires inspection
- An open or shorted circuit must be located
- The thermistor tests correctly but F22 continues
A technician can isolate the thermistor, check its resistance, inspect wiring continuity, and determine whether the fault originates with the sensor, connections, wiring, or control side of the circuit.
Key Point
F22 indicates a Steam Sensor Failure involving the Left Steam Sensor.
The direct diagnostic information specifies:
F22: Left Steam Sensor Open
Cause: Open or shorted circuit condition of the steam thermistor
Initial checks: Steam thermistor and Main PCB connections
Thermistor resistance: 1.09 kΩ at 77°F
F22 does not automatically mean the thermistor itself has failed. The sensor, wiring, connectors, and Main PCB connections should be evaluated as a complete circuit.
F24 — Lower Oven Meat Probe Shorted Error
The F24 error code indicates a shorted condition in the lower oven meat probe sensor circuit of an LG range or oven.
The meat probe system allows the electronic control to monitor the internal temperature of food during probe-assisted cooking. The Main PCB expects to receive a valid electrical signal through the Lower Oven Meat Probe Sensor circuit.
If the control detects a shorted condition in that circuit, the appliance may display F24.
What the F24 Error Code Means
F24 specifically identifies an electrical problem involving the Lower Oven Meat Probe Sensor circuit.
The Main PCB monitors the probe circuit and interprets its electrical characteristics as temperature information.
When the circuit becomes shorted, the signal falls outside the condition expected by the control.
The diagnostic path should therefore focus on:
Meat Probe → Lower Oven Meat Probe Sensor Jack → Wiring / Connections → Main PCB
A shorted condition anywhere along this path may cause F24.
Common Causes
Areas that may require inspection include:
- Lower Oven Meat Probe Sensor
- Shorted meat probe
- Meat Probe Sensor Jack
- Damaged probe cable
- Shorted wiring
- Damaged wire insulation
- Sensor jack connections
- Main PCB connections
- Poor or damaged electrical terminals
F24 does not automatically prove that the Main PCB or meat probe itself has failed.
The complete probe circuit should be inspected to locate the shorted condition.
What You Can Check
If F24 appears, record the circumstances surrounding the error.
Useful observations include:
- Whether the meat probe was connected
- Whether F24 appeared when the probe was inserted
- Whether the error appeared when probe cooking was started
- Whether removing and reconnecting the probe changes the condition
- Whether the probe cable has visible damage
- Whether the probe connector appears bent or damaged
- Whether the probe jack appears damaged
- Whether F24 returns consistently
- The complete LG model number
These observations can help determine whether the problem is associated with the removable probe or the oven’s internal probe circuit.
Check the Meat Probe and Cable
Because F24 represents a shorted meat probe circuit, the external probe and its cable should be visually inspected.
Look for:
- Damaged cable insulation
- Crushed or pinched cable
- Bent connector
- Damaged probe
- Contamination around the connector
- Signs of overheating or physical damage
A physically damaged probe or cable may affect the electrical signal reaching the oven control.
Do not continue using a visibly damaged meat probe.
Check the Lower Oven Meat Probe Sensor Jack
The Lower Oven Meat Probe Sensor Jack is an important part of the F24 diagnostic path.
The jack provides the electrical connection between the removable meat probe and the oven’s internal sensing circuit.
Inspect the jack and its connections for:
- Damaged contacts
- Bent terminals
- Loose connector
- Damaged wiring
- Poor electrical contact
- Shorted terminals
- Contamination or physical damage
A problem at the jack can create an abnormal electrical condition even when the removable meat probe itself is not defective.
Check the Main PCB Connections
The direct diagnostic information also directs attention to the Main PCB connections.
The Main PCB must receive the meat probe signal through the internal wiring and connectors.
The complete path can be represented as:
Lower Oven Meat Probe → Sensor Jack → Wiring Harness → Main PCB
A short circuit anywhere in this path can prevent the control from interpreting the probe signal correctly.
Both the probe-side and Main PCB-side connections should therefore be inspected.
What Does a Shorted Probe Circuit Mean?
A short circuit occurs when the electrical path has an unintended low-resistance connection.
Within the meat probe circuit, this can result from conditions such as:
- Internally shorted probe
- Damaged cable
- Conductors contacting each other
- Damaged wiring insulation
- Shorted connector terminals
- Problem inside the Sensor Jack circuit
The objective of diagnosis is to determine where the shorted condition exists, rather than replacing components based solely on the F24 code.
Probe vs. Jack vs. Wiring Diagnosis
The F24 circuit can be divided into several diagnostic areas.
Probe side:
The removable meat probe or its cable may be damaged or shorted.
Jack side:
The Lower Oven Meat Probe Sensor Jack may have damaged or shorted contacts.
Wiring side:
Internal wiring between the jack and Main PCB may be damaged.
Control side:
Connections at the Main PCB may require inspection.
Isolating these sections can help determine where the abnormal electrical condition originates.
No Resistance Specification Is Provided for F24
The direct F24 diagnostic information does not provide a specific resistance value for the meat probe.
It also does not provide a voltage specification for this code.
Therefore, resistance values from:
- Oven temperature sensors
- Steam thermistors
- Door Lock Motors
- Other LG error codes
should not be applied to F24.
Any additional electrical specifications should come from the service information for the exact LG model being diagnosed.
F18 vs. F24
F18 and F24 both involve the Lower Oven Meat Probe Sensor, but they represent different electrical conditions.
F18 — Lower Oven Meat Probe Error
→ The Main PCB does not receive the expected signal from the Lower Oven Meat Probe Sensor for more than one minute after cooking starts.
F24 — Lower Oven Meat Probe Shorted Error
→ The control detects a shorted condition in the Lower Oven Meat Probe Sensor circuit.
This distinction is important.
F18 is primarily associated with a missing probe signal, while F24 specifically directs diagnosis toward a shorted probe circuit.
Both codes require attention to the Meat Probe Sensor Jack, wiring, connections, and Main PCB signal path.
F24 Diagnostic Sequence
A practical diagnostic sequence is:
F24 displayed
→ Confirm the problem involves the lower oven meat probe system
→ Inspect the meat probe and cable
→ Inspect the probe connector
→ Check the Lower Oven Meat Probe Sensor Jack
→ Inspect jack connections
→ Check wiring for a shorted condition
→ Check Main PCB connections
→ Isolate the probe, jack, and wiring sections as necessary
→ Continue with model-specific electrical testing if the short cannot be located
This approach helps identify the actual location of the short rather than replacing the meat probe immediately.
Can You Clear the F24 Code?
Disconnecting and restoring power may reset the electronic control and temporarily remove F24 from the display.
However, a reset cannot repair a persistent:
- Shorted meat probe
- Damaged probe cable
- Shorted Sensor Jack
- Damaged wiring
- Connector problem
If F24 returns, the lower oven meat probe circuit should be diagnosed.
Repeated power cycling should not be considered a permanent solution.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F24 repeatedly returns
- The error appears whenever the meat probe is connected
- The probe or Sensor Jack appears damaged
- Internal wiring requires inspection
- A short circuit must be located
- The external probe appears normal but F24 continues
A technician can isolate individual parts of the probe circuit and determine whether the short originates in the probe, Sensor Jack, wiring, connections, or control side of the circuit.
Key Point
F24 indicates a shorted condition in the Lower Oven Meat Probe Sensor circuit.
The diagnostic path should focus on:
Lower Oven Meat Probe → Meat Probe Sensor Jack → Wiring / Connections → Main PCB
Check the Lower Oven Meat Probe Sensor Jack and Main PCB connections and inspect the circuit for the source of the short.
The direct F24 information does not provide a specific resistance or voltage specification, so model-specific service information should be used if additional electrical testing is required.
F25 — Lower Oven Heating Error
The F25 error code indicates a heating problem in the lower oven of an LG range or oven.
When preheating begins, the electronic control expects the lower oven temperature to rise within a defined period of time. If the temperature does not increase sufficiently, the control may determine that the lower oven is not heating normally and display F25.
According to the direct diagnostic information, F25 is triggered when the lower oven temperature does not exceed 150°F within five minutes after preheating begins.
What the F25 Error Code Means
F25 is specifically a Lower Oven Heating Error.
The control monitors temperature during the initial preheat period and expects the lower oven to reach more than:
150°F within 5 minutes
If that temperature threshold is not reached, the appliance interprets the condition as an abnormal heating response.
This makes F25 different from a temperature sensor error. The code is primarily concerned with whether the lower oven is actually heating quickly enough during preheat.
Common Causes
Diagnosis should focus on the lower oven heating system and its electrical connections.
Possible areas requiring inspection include:
- Bake heating element
- Broil heating element
- Heating element wiring
- Loose electrical connections
- Damaged wiring
- Main PCB connections
- Heating control circuit
- Power delivery to the heating components
The F25 code does not automatically identify which heating component has failed.
The complete lower oven heating circuit should be evaluated.
What You Can Check
If F25 appears, observe how the lower oven behaves during preheating.
Useful information includes:
- Whether the oven produces any heat
- Whether preheating is unusually slow
- Whether one heating element appears to operate while another does not
- Whether F25 appears approximately five minutes after preheating begins
- Whether the oven temperature rises at all
- Whether the problem occurs every time the lower oven is used
- Whether Bake and Broil behave differently
- The complete LG model number
These observations can help determine whether heating has stopped completely or is simply insufficient.
Check Whether the Lower Oven Is Heating
The first useful distinction is whether the lower oven produces heat at all.
If the oven remains essentially cold during preheating, diagnosis should focus on components and circuits responsible for supplying heat.
If the oven heats but does so too slowly, the technician should determine whether all heating components that should participate in preheating are operating correctly.
The defining F25 condition remains:
Lower oven temperature fails to exceed 150°F within five minutes of starting preheat.
Check the Heating Elements
The lower oven heating elements are important parts of the F25 diagnostic path.
Depending on the particular LG model and cooking mode, the oven may use different heating components during preheating.
A technician may need to inspect the relevant elements for:
- Visible damage
- Open element
- Burned connection
- Damaged terminal
- Failed electrical connection
- Abnormal element operation
A heating element that cannot operate normally may prevent the oven from reaching the expected temperature within the allowed time.
Check the Heating Element Wiring
A functional heating element cannot produce heat if its electrical circuit is interrupted.
Inspect the associated wiring for:
- Loose terminals
- Burned connectors
- Damaged wires
- Broken conductors
- Heat-damaged insulation
- Poor terminal contact
- Disconnected harnesses
High-current oven heating circuits can develop significant heat at a poor electrical connection, so burned or discolored terminals should not be ignored.
Check the Main PCB Connections
The Main PCB participates in controlling the lower oven heating system.
Connections at the electronic control should therefore be inspected as part of F25 diagnosis.
A simplified heating-control path is:
Main PCB / Heating Control → Wiring → Heating Components → Oven Temperature Increase
If the heating components are functional but are not being energized correctly, further diagnosis of the control side may be necessary.
However, the Main PCB should not automatically be replaced simply because F25 appears.
Heating components, wiring, and connections should be checked first.
Heating Element vs. Control Problem
F25 diagnosis should distinguish between a load-side problem and a control-side problem.
Load side:
- Heating element
- Element terminal
- Element wiring
- Electrical connection
Control side:
- Main PCB connection
- Heating control circuit
- Electrical supply to the heating component
If a heating element receives the appropriate power but does not produce the expected heat, the element becomes a stronger suspect.
If the expected power is not reaching a functional element, diagnosis should move toward wiring and control.
Temperature Sensor Considerations
F25 is not primarily defined as a temperature sensor error.
The code is triggered because the lower oven does not reach the required temperature threshold during preheating.
However, the electronic control determines oven temperature using its temperature-sensing system.
Therefore, if the heating components and their electrical circuits operate correctly but F25 persists, model-specific diagnosis may also need to confirm that the control is receiving accurate oven temperature information.
A temperature sensor should not be replaced solely because F25 appears.
F25 Diagnostic Sequence
A practical diagnostic sequence is:
F25 displayed
→ Confirm the error involves the lower oven
→ Start with the circumstances of the preheat failure
→ Determine whether the oven produces heat
→ Check the relevant heating elements
→ Inspect heating element terminals and wiring
→ Check Main PCB connections
→ Determine whether the heating components are being energized correctly
→ Verify temperature feedback if the heating system operates normally
→ Continue with model-specific control diagnosis if necessary
The key diagnostic question is why the lower oven cannot exceed 150°F within five minutes of preheating.
F16 vs. F25
F16 and F25 represent opposite types of lower oven temperature problems.
F16 — Lower Oven Too Hot
→ Temperature remains above 650°F for more than two continuous minutes, except during Self Clean.
F25 — Lower Oven Heating Error
→ Temperature does not exceed 150°F within five minutes after preheating begins.
This distinction makes the diagnostic direction very different.
F16 begins with an over-temperature condition.
F25 begins with insufficient temperature rise during preheating.
F19 vs. F25
F19 and F25 can also be distinguished by what the control is detecting.
F19 → Lower Oven Temperature Sensor Error
F25 → Lower Oven is not heating quickly enough during preheat
F19 directs diagnosis primarily toward the temperature sensor circuit.
F25 directs diagnosis primarily toward the lower oven heating system.
This distinction should be maintained even though both codes ultimately rely on temperature information from the oven.
Can You Clear the F25 Code?
Disconnecting and restoring power may reset the electronic control and temporarily remove F25.
However, a reset cannot repair:
- Failed heating element
- Damaged heating wiring
- Burned electrical connection
- Heating control problem
- Persistent preheat failure
If F25 returns during preheating, the lower oven heating system should be diagnosed.
Repeated power cycling should not be considered a permanent repair.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F25 repeatedly returns
- The lower oven does not heat
- Preheating is unusually slow
- One or more heating components do not operate
- Heating element wiring requires inspection
- Internal voltage testing is required
- The heating system appears functional but F25 continues
Electric oven heating circuits can operate at hazardous mains voltage, so internal live-voltage testing should only be performed by someone qualified to safely service ranges and ovens.
Key Point
F25 indicates a Lower Oven Heating Error.
The defining condition is:
Lower oven temperature does not exceed 150°F within 5 minutes after preheating begins.
Diagnosis should focus on the lower oven heating components, their wiring and connections, and the Main PCB/control side of the heating circuit.
F25 does not automatically identify a specific failed part. The reason the lower oven cannot achieve the expected temperature rise should be determined before components are replaced.
F27 — Cooling Fan Stalled or Locked During Self Clean
The F27 error code indicates that the oven control cannot detect normal cooling fan operation during the Self Clean cycle.
The cooling fan helps manage temperatures around internal oven components and electronics while the appliance operates under high-temperature conditions.
If cooling fan operation cannot be detected for more than one minute, the control may stop normal operation and display F27.
What the F27 Error Code Means
LG identifies F27 as:
Cooling Fan Stalled or Locked During Self Clean
The defining condition is:
Cooling fan operation cannot be detected for over 1 minute.
This makes F27 specifically related to the cooling fan system during Self Clean, rather than the convection fan used to circulate heated air inside the oven cavity.
Common Causes
The direct diagnostic path focuses on the Cooling Fan and its connection to the Main PCB.
Areas that may require inspection include:
- Cooling Fan
- Cooling Fan harness
- Fan electrical connector
- Wiring between the Cooling Fan and Main PCB
- Loose electrical connection
- Damaged wiring
- Poor terminal contact
- Mechanical obstruction preventing fan operation
- Main PCB connection
F27 does not automatically prove that the Cooling Fan motor itself has failed.
The fan may be unable to operate because of a mechanical restriction, wiring problem, loose connector, or control-side issue.
What You Can Check
If F27 appears, note exactly when the error occurs.
Useful observations include:
- Whether F27 appears only during Self Clean
- Whether the Cooling Fan can be heard operating
- Whether the fan starts and then stops
- Whether unusual fan noises are present
- Whether there is rattling, scraping, or humming
- Whether F27 returns after another Self Clean attempt
- Whether the appliance recently underwent service
- The complete LG model number
Because the code specifically relates to Self Clean operation, the timing of the error is particularly useful for diagnosis.
Check the Cooling Fan Harness
The direct LG diagnostic information instructs technicians to:
Check the harness at the Cooling Fan and Main PCB.
The harness provides the electrical connection between the cooling fan system and the electronic control.
Inspect the fan-side connection for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat-damaged connector
- Poor electrical contact
A connection problem can prevent normal fan operation or prevent the control from detecting that the fan is operating.
Check the Main PCB Connection
The other end of the Cooling Fan harness should be inspected at the Main PCB.
A simplified diagnostic path is:
Main PCB → Cooling Fan Harness → Cooling Fan
If the electrical path is interrupted, the fan may not receive the required control or power needed for normal operation.
The Main PCB connection should therefore be checked before concluding that either the fan or control board requires replacement.
Check for a Stalled or Locked Cooling Fan
The F27 description specifically uses the terms stalled or locked.
A fan may be electrically functional but unable to rotate normally because of a mechanical problem.
With the appliance safely powered off, inspection may reveal:
- Obstruction around the fan
- Fan blade interference
- Damaged fan blade
- Debris restricting movement
- Mechanical binding
- Fan motor that cannot rotate freely
Any physical restriction should be corrected before additional electrical diagnosis.
Cooling Fan vs. Convection Fan
The Cooling Fan should not be confused with the Convection Fan.
The convection fan circulates heated air within the oven cavity to support convection cooking.
The cooling fan serves a different purpose by helping manage temperatures around oven components and electronics.
This distinction is important because another LG error code, F17, relates to a Lower Convection Fan Error.
F17 → Lower Convection Fan
F27 → Cooling Fan during Self Clean
The two codes should therefore remain separate diagnostic entries.
Why F27 Can Appear During Self Clean
Self Clean exposes the oven to much higher temperatures than ordinary cooking cycles.
Because of these elevated temperatures, proper cooling-system operation becomes particularly important.
The control monitors cooling fan operation during this process.
If fan operation cannot be detected for more than one minute, F27 may be generated.
The code should therefore not be ignored by repeatedly attempting to restart Self Clean.
Fan Motor vs. Wiring Diagnosis
A useful diagnostic approach is to determine whether the problem originates with the fan itself or the circuit controlling it.
If the Cooling Fan cannot rotate because it is mechanically locked, diagnosis should focus on the fan assembly and obstruction.
If the fan moves freely but does not operate when required, inspect:
- Fan harness
- Electrical connectors
- Wiring
- Main PCB connection
If all external wiring and connections are correct, further model-specific electrical diagnosis may be required.
No Universal Resistance or Voltage Specification Is Provided
The direct F27 source does not provide a Cooling Fan resistance or voltage specification.
Therefore, electrical values from:
- Convection fan motors
- Door lock motors
- Temperature sensors
- Other LG oven error codes
should not be applied to F27.
If voltage, resistance, or other electrical measurements are required, use the service information for the exact LG model.
F27 Diagnostic Sequence
A practical diagnostic sequence is:
F27 displayed during Self Clean
→ Confirm the exact code and model number
→ Determine whether the Cooling Fan operates
→ Listen for abnormal fan noise
→ Power off the appliance before physical inspection
→ Check for a stalled or mechanically locked fan
→ Inspect the Cooling Fan harness
→ Inspect the Main PCB harness connection
→ Check wiring and terminals for damage
→ Continue with model-specific fan/control diagnosis if necessary
The goal is to determine why normal Cooling Fan operation cannot be detected for more than one minute.
F17 vs. F27
These two codes both involve fans, but they refer to different systems.
F17 — Lower Convection Fan Error
The control cannot detect lower convection fan operation for more than one minute.
F27 — Cooling Fan Stalled or Locked During Self Clean
The control cannot detect Cooling Fan operation for more than one minute during Self Clean.
The key distinction is:
F17 → Convection airflow inside the oven system
F27 → Cooling system associated with Self Clean operation
This distinction should be maintained during troubleshooting.
Can You Clear the F27 Code?
Disconnecting and restoring power may reset the electronic control and temporarily clear F27.
However, a reset cannot repair:
- Mechanically locked Cooling Fan
- Failed fan system
- Damaged wiring
- Loose harness connection
- Poor Main PCB connection
- Persistent fan control problem
If F27 returns, especially during Self Clean, the Cooling Fan system should be diagnosed before another Self Clean cycle is attempted.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F27 repeatedly appears
- The Cooling Fan does not operate
- The fan makes abnormal noises
- The fan appears mechanically locked
- Internal wiring requires inspection
- Main PCB connections require diagnosis
- Electrical testing of the fan circuit is necessary
Because Self Clean involves very high temperatures and internal oven electrical systems can contain hazardous mains voltage, internal diagnosis should be performed only after appropriate electrical safety precautions are taken.
Key Point
F27 indicates that Cooling Fan operation cannot be detected for more than one minute during Self Clean.
The primary diagnostic path is:
Cooling Fan → Harness / Wiring → Main PCB
Check whether the fan is stalled or mechanically locked, then inspect the harness connections at both the Cooling Fan and Main PCB.
The direct F27 information does not provide a universal resistance or voltage specification, so model-specific service information should be used for additional electrical testing.
F3 — Touch Pad Sensor Key Error
The F3 error code usually indicates a touch pad or keypad input problem on an LG range or oven.
For most LG models, F3 appears when the electronic control detects an abnormal key condition for approximately 60 seconds. This may involve a stuck key, missing key input, or another keypad-related error.
However, several older LG electric range models use F3 for a completely different fault, so the model number must be checked before troubleshooting.
What the F3 Error Code Means
For most LG ranges and ovens, F3 means:
Touch Pad Sensor Key Error
The control has detected a keypad condition such as:
- A key remaining stuck
- No expected key input
- Another abnormal key condition
The direct diagnostic information specifies that this condition must remain present for approximately:
60 seconds
before F3 is generated.
This makes F3 primarily a user-interface / keypad diagnostic code on most models.
Important Model Exception
F3 has a different meaning on several older LG electric ranges.
For these models:
- LRE3012
- LRE30451
- LRE30453
- LRE30757
F3 means:
Oven Thermistor Error
For these specific models, troubleshooting should follow the oven thermistor diagnostic procedure rather than the keypad procedure.
For all other models, F3 should be diagnosed as a keypad / touch pad sensor key error.
Common Causes
For models where F3 is a Touch Pad Sensor Key Error, possible areas to investigate include:
- Stuck keypad button
- Key remaining continuously activated
- Damaged touch pad
- Damaged display/control interface
- Physical damage to the keypad surface
- Contamination affecting a key
- Abnormal keypad input
- User-interface connection problem
The code should not automatically be interpreted as a failed Main PCB.
The keypad and display area should be inspected first.
What You Can Check
Start by checking whether any control-panel key appears physically abnormal.
Look for:
- Button that appears stuck
- Key that does not return normally
- Damaged keypad surface
- Cracked control panel
- Signs of impact damage
- Key that responds differently from the others
- Control panel that produces unexpected inputs
- F3 appearing without anyone touching the controls
If one key appears permanently activated, the control may interpret that condition as a continuous keypad input and eventually display F3.
Check the Display for Damage
The direct F3 troubleshooting instruction specifically states:
Check display for damage.
Inspect the display and control-panel area for visible signs of:
- Cracking
- Physical impact
- Damaged keypad surface
- Distorted buttons
- Separation of control-panel layers
- Other visible damage
Physical damage can interfere with normal keypad operation and cause the control to receive an abnormal or continuous key signal.
Check for a Stuck Key
A stuck key is one of the conditions specifically associated with F3.
Check whether each key:
- Moves or responds normally
- Returns to its normal state
- Produces the expected response
- Appears permanently pressed
- Activates without intentional input
A key that remains electrically or mechanically active may cause the control to detect a continuous input condition.
Why the 60-Second Condition Matters
The source specifically identifies a keypad error condition lasting:
60 seconds
This helps distinguish F3 from a brief or accidental key press.
The control is looking for a persistent abnormal input rather than simply reacting to normal momentary interaction with the keypad.
If a key remains stuck or an abnormal input persists for approximately one minute, the electronic control can recognize the condition as a fault.
Touch Pad vs. Main Control Diagnosis
F3 should not immediately lead to replacement of the Main PCB.
For most models, diagnosis should begin with the user-interface side:
Touch Pad / Keypad → Interface Connections → Electronic Control
First determine whether:
- A key is physically stuck
- The display is damaged
- The keypad behaves abnormally
- There is an obvious interface problem
If the keypad and display appear normal but F3 repeatedly returns, further model-specific diagnosis of the interface and control system may be necessary.
What If No Key Appears Stuck?
A keypad problem may not always be visible externally.
If all buttons appear normal but F3 continues, further diagnosis may require inspection of:
- Touch pad assembly
- Keypad connections
- Interface wiring
- Connectors
- Electronic control interface
The exact architecture can vary between LG models, so the complete model number should be used when proceeding beyond basic external inspection.
F3 on Older LG Electric Ranges
The four older models require special attention:
LRE3012, LRE30451, LRE30453, and LRE30757
On these ranges:
F3 = Oven Thermistor Error
The direct source instructs technicians to use the F1 error-code troubleshooting procedure for the oven thermistor fault.
Therefore, applying keypad troubleshooting to these models would send diagnosis in the wrong direction.
Always confirm the model number before interpreting F3.
F1 vs. F3 Model Exception
The relationship between F1 and F3 is unusual on these older models.
For the listed older electric ranges:
F3 → Oven Thermistor Error
F1 → Keypad Error
For most other LG ranges and ovens:
F3 → Touch Pad Sensor Key Error
This is why the model number is particularly important for these two error codes.
The same displayed code can identify a completely different system depending on the appliance model.
F3 Diagnostic Sequence
For most LG models:
F3 displayed
→ Confirm the complete model number
→ Determine whether the appliance is one of the four older electric ranges
→ If not, treat F3 as a Touch Pad Sensor Key Error
→ Inspect the display for damage
→ Check for a stuck or continuously activated key
→ Evaluate keypad behavior
→ If the problem persists, continue with model-specific interface/control diagnosis
For:
LRE3012 / LRE30451 / LRE30453 / LRE30757
use the oven thermistor diagnostic path instead.
Can You Clear the F3 Code?
Disconnecting power and restarting the appliance may temporarily clear F3 if the abnormal keypad condition is no longer present.
However, resetting the appliance cannot repair:
- Stuck key
- Damaged touch pad
- Damaged display
- Persistent keypad input problem
- Internal interface problem
If F3 repeatedly returns, the keypad/control interface should be diagnosed.
For the four older models listed above, the oven thermistor system should be diagnosed instead.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F3 repeatedly returns
- A key appears permanently stuck
- The display or keypad is damaged
- The control responds without user input
- Basic inspection reveals no obvious problem
- Internal interface diagnosis is required
- The appliance is one of the older models where F3 indicates an oven thermistor error
The exact model number should be provided to the technician because the meaning of F3 is model-dependent.
Key Point
For most LG ranges and ovens:
F3 = Touch Pad Sensor Key Error
The defining condition is:
Stuck key, no key input, or another key error for approximately 60 seconds.
The initial troubleshooting direction is:
Check the display for damage and inspect the keypad for abnormal or stuck keys.
However, on these older electric ranges:
LRE3012, LRE30451, LRE30453, LRE30757
F3 = Oven Thermistor Error, and the oven thermistor diagnostic procedure should be followed instead.
F33 — Front Induction Burner Temperature Sensor Error
The F33 error code indicates a problem with the front induction burner temperature sensor circuit in an LG range or cooktop system.
The induction system uses a temperature sensor to monitor operating conditions around the front induction burner. The Cooktop System PCB expects to receive a valid signal from this sensor.
If the temperature sensor is defective or the sensor circuit is missing the required voltage from the control board, the appliance may display F33.
What the F33 Error Code Means
LG identifies F33 as:
Front Induction Burner Temperature Sensor Error
The direct diagnostic information identifies two primary possibilities:
- The temperature sensor is defective
- The sensor is missing voltage from the main board
This means F33 should not automatically be interpreted as a failed sensor.
The complete circuit should be considered:
Cooktop System PCB → Sensor Circuit / Wiring → Front Induction Temperature Sensor
Both the sensor and its electrical supply need to be evaluated.
Common Causes
Possible areas requiring inspection include:
- Front Induction Burner Temperature Sensor
- Sensor wiring
- Loose sensor connector
- Damaged wiring
- Poor terminal contact
- Missing sensor supply voltage
- Cooktop System PCB connection
- Control-side problem preventing the expected sensor voltage
The diagnostic goal is to determine whether the sensor itself is outside specification or whether the sensor is not receiving the required electrical supply.
What You Can Check
If F33 appears, record how the induction cooking system behaves.
Useful observations include:
- Whether the front induction burner operates
- Whether F33 appears immediately after power-up
- Whether the code appears when the front burner is activated
- Whether other induction burners operate normally
- Whether the problem is isolated to the front burner
- Whether F33 returns after restarting the appliance
- Whether the cooktop was recently serviced
- The complete LG model number
If other induction zones operate normally while the front burner repeatedly generates F33, this information can help narrow the diagnostic area.
Check the Front Induction Temperature Sensor
The direct F33 diagnostic procedure provides a specific resistance reference for the induction temperature sensor:
57 kΩ at 77°F.
This value provides an important reference when evaluating the sensor.
At approximately:
77°F → Induction Temperature Sensor ≈ 57 kΩ
Because this is a temperature-sensitive sensor, its resistance changes with temperature.
For a meaningful comparison with the published specification, the sensor should therefore be close to 77°F when measured.
Why Temperature Matters During Resistance Testing
The specified 57 kΩ value applies at 77°F.
If the sensor is substantially warmer or colder when tested, its resistance may differ from the reference value even when the sensor is functioning normally.
Allowing the cooktop to cool before testing provides a more useful comparison with the published specification.
A resistance reading should therefore always be interpreted together with the sensor temperature.
Check for 5 VDC From the Cooktop System PCB
The second specific F33 diagnostic measurement is:
5 VDC from the Cooktop System PCB.
This measurement helps distinguish a sensor problem from a sensor-supply or control-side problem.
The diagnostic logic is:
Sensor resistance incorrect at the specified temperature
→ Investigate the Front Induction Temperature Sensor.
Sensor resistance appears correct but required 5 VDC is missing
→ Investigate the sensor circuit, connections, wiring, and Cooktop System PCB side.
This distinction can prevent unnecessary replacement of a functional sensor.
Check the Sensor Wiring and Connections
Before replacing components, inspect the electrical path between the temperature sensor and Cooktop System PCB.
Look for:
- Loose connectors
- Connector not fully seated
- Broken wires
- Damaged insulation
- Bent terminals
- Backed-out terminals
- Poor electrical contact
- Heat-damaged connections
A sensor can measure correctly but still fail to provide usable information to the control if its wiring or connector is damaged.
Sensor vs. Cooktop System PCB Diagnosis
F33 provides two useful diagnostic reference points:
Sensor: approximately 57 kΩ at 77°F
Cooktop System PCB: approximately 5 VDC sensor supply
These values help divide diagnosis between the sensing side and control side.
A simplified diagnostic path is:
Cooktop System PCB (5 VDC) → Wiring / Connector → Temperature Sensor (57 kΩ @ 77°F)
If the sensor is outside specification, the sensor becomes the primary area of investigation.
If the sensor tests correctly but the required voltage is absent, diagnosis should move toward the wiring, connections, and Cooktop System PCB.
What If Both Measurements Are Correct?
If the sensor measures approximately 57 kΩ at 77°F and the expected 5 VDC is present, further diagnosis may be necessary.
Inspect:
- Sensor connector contact
- Wiring continuity
- Intermittent connection problems
- Harness condition
- Cooktop System PCB connector
An intermittent circuit problem may allow individual measurements to appear normal while F33 continues to occur during operation.
Model-specific service information should be used if the basic sensor and supply checks are normal but the code persists.
F33 vs. CF1–CF4
F33 is closely related to the CF1–CF4 induction temperature sensor codes already covered.
The direct source gives the same basic diagnostic values:
57 kΩ at 77°F
5 VDC from the Cooktop System PCB
However, the location descriptions differ:
CF1 → Left Front Induction Burner Temperature Sensor
CF2 → Left Rear Induction Burner Temperature Sensor
CF3 → Right Front Induction Burner Temperature Sensor
CF4 → Right Rear Induction Burner Temperature Sensor
F33 → Front Induction Burner Temperature Sensor
The exact displayed code and appliance model should therefore be used to identify which sensor circuit requires diagnosis.
F33 Diagnostic Sequence
A practical diagnostic sequence is:
F33 displayed
→ Confirm the exact model number
→ Identify the Front Induction Burner Temperature Sensor
→ Allow the cooktop to cool near the specified test temperature
→ Inspect the sensor and its connector
→ Check sensor wiring
→ Measure sensor resistance
→ Compare with approximately 57 kΩ at 77°F
→ Check for 5 VDC from the Cooktop System PCB
→ If sensor resistance is abnormal, investigate the sensor
→ If 5 VDC is missing, investigate wiring, connections, and the PCB side
→ If both measurements are correct, continue with model-specific circuit diagnosis
This sequence separates the sensor itself from its power and signal path.
Can You Clear the F33 Code?
Disconnecting and restoring power may temporarily clear F33.
However, resetting the appliance cannot repair:
- Defective temperature sensor
- Damaged sensor wiring
- Loose connector
- Missing 5 VDC supply
- Persistent Cooktop System PCB circuit problem
If F33 returns, the front induction temperature sensor circuit should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F33 repeatedly returns
- The front induction burner does not operate correctly
- Sensor resistance needs to be measured
- The 5 VDC supply requires testing
- Internal wiring requires inspection
- The sensor tests normally but F33 continues
Electrical testing inside an induction cooking appliance should be performed using appropriate electrical safety procedures.
Key Point
F33 indicates a Front Induction Burner Temperature Sensor Error.
The direct diagnostic information provides two important specifications:
Induction Temperature Sensor: 57 kΩ at 77°F
Cooktop System PCB sensor supply: 5 VDC
F33 does not automatically mean the temperature sensor has failed. Diagnosis should determine whether the sensor is within specification and whether the required 5 VDC supply is present before identifying the failed part.
F34 — Rear Induction Burner Temperature Sensor Error
The F34 error code indicates a problem with the rear induction burner temperature sensor circuit in an LG range or oven.
The induction system uses a temperature sensor to monitor operating conditions around the rear induction burner. The Cooktop System PCB expects a valid electrical signal from this sensor.
If the sensor is defective or the sensor circuit is missing the required voltage from the control board, the appliance may display F34.
What the F34 Error Code Means
LG identifies F34 as:
Rear Induction Burner Temperature Sensor Error
The direct diagnostic information identifies two primary conditions:
- The temperature sensor is defective
- The sensor is missing voltage from the main board
This means F34 does not automatically confirm that the temperature sensor itself has failed.
Diagnosis should consider the complete circuit:
Cooktop System PCB → Wiring / Connections → Rear Induction Temperature Sensor
Both the sensor and its electrical supply should be checked before determining which component is responsible.
Common Causes
Possible areas requiring inspection include:
- Rear Induction Burner Temperature Sensor
- Sensor wiring
- Loose sensor connector
- Damaged wiring
- Poor terminal contact
- Missing sensor supply voltage
- Cooktop System PCB connection
- Control-side problem affecting the sensor circuit
A wiring or voltage-supply problem can produce the same F34 code as a defective temperature sensor.
What You Can Check
If F34 appears, note how the induction cooktop behaves.
Useful observations include:
- Whether the rear induction burner operates
- Whether F34 appears when the rear burner is activated
- Whether the code appears immediately after power-up
- Whether the front induction burner operates normally
- Whether the problem is isolated to the rear burner
- Whether F34 returns after restarting the appliance
- Whether the cooktop was recently serviced
- The complete LG model number
If the front induction burner operates normally while the rear burner repeatedly generates F34, this can help narrow the diagnostic area.
Check the Rear Induction Temperature Sensor
LG provides a specific resistance reference for the induction temperature sensor:
57 kΩ at 77°F
This is the primary sensor-side measurement for F34.
At approximately:
77°F → Induction Temperature Sensor ≈ 57 kΩ
The resistance should be measured with the appliance safely disconnected from power and the sensor near the specified temperature.
Why Sensor Temperature Matters
The induction temperature sensor is temperature-sensitive, so its resistance changes as its temperature changes.
The published 57 kΩ reference applies at:
77°F
A sensor measured while the cooktop is still warm may therefore produce a resistance different from 57 kΩ without necessarily being defective.
Allowing the cooktop and sensor to cool near room temperature provides a more meaningful comparison with the published specification.
Check for 5 VDC From the Cooktop System PCB
The second specific diagnostic value provided for F34 is:
5 VDC from the Cooktop System PCB
This measurement evaluates the control-side supply to the sensor circuit.
The basic diagnostic logic is:
Sensor resistance incorrect near 77°F
→ Investigate the Rear Induction Temperature Sensor.
Sensor resistance correct but 5 VDC is missing
→ Investigate wiring, connectors, and the Cooktop System PCB side of the circuit.
Checking both values helps avoid replacing a functional sensor when the actual problem is a missing sensor supply.
Check the Sensor Wiring and Connections
The electrical path between the Rear Induction Temperature Sensor and Cooktop System PCB should also be inspected.
Look for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat-damaged connector
- Poor electrical contact
A functional sensor may still generate F34 if its signal cannot reach the control correctly.
Sensor vs. Cooktop System PCB Diagnosis
F34 provides two useful diagnostic reference points:
Rear Induction Temperature Sensor:
57 kΩ at 77°F
Cooktop System PCB:
5 VDC
The basic circuit can be viewed as:
Cooktop System PCB (5 VDC) → Wiring / Connector → Rear Induction Temperature Sensor (57 kΩ @ 77°F)
If the sensor is outside specification, investigate the sensor.
If the sensor is within specification but the required 5 VDC is absent, diagnosis should move toward the wiring, connections, and control side.
What If Both Measurements Are Correct?
If approximately 57 kΩ at 77°F is measured at the sensor and the expected 5 VDC is present, inspect the rest of the circuit for intermittent problems.
Possible areas include:
- Sensor connector
- Wiring continuity
- Harness terminals
- Intermittent connection
- Cooktop System PCB connector
If the basic electrical checks are normal but F34 continues, use service information for the exact LG model for further diagnosis.
F33 vs. F34
F33 and F34 form a closely related pair.
F33 → Front Induction Burner Temperature Sensor Error
F34 → Rear Induction Burner Temperature Sensor Error
Both use the same diagnostic specifications:
Temperature Sensor → 57 kΩ at 77°F
Cooktop System PCB → 5 VDC
The primary difference is the burner location.
If F33 appears, diagnosis focuses on the front induction burner sensor circuit.
If F34 appears, diagnosis focuses on the rear induction burner sensor circuit.
F34 vs. CF1–CF4
F34 also belongs to the same general family of induction temperature sensor faults as CF1–CF4.
Those codes identify more specific burner positions:
CF1 → Left Front
CF2 → Left Rear
CF3 → Right Front
CF4 → Right Rear
F34 identifies the affected location simply as:
Rear Induction Burner
Because LG models can use different cooktop configurations, the exact displayed code and complete model number should be used to identify the correct sensor circuit.
F34 Diagnostic Sequence
A practical diagnostic sequence is:
F34 displayed
→ Confirm the exact LG model
→ Identify the Rear Induction Burner Temperature Sensor
→ Allow the cooktop to cool near room temperature
→ Inspect the sensor connector and wiring
→ Measure sensor resistance
→ Compare with 57 kΩ at 77°F
→ Check for 5 VDC from the Cooktop System PCB
→ If sensor resistance is abnormal, investigate the sensor
→ If 5 VDC is missing, investigate wiring, connections, and the PCB side
→ If both measurements are correct, continue with model-specific circuit diagnosis
This sequence helps separate a sensor fault from a sensor-supply or wiring problem.
Can You Clear the F34 Code?
Disconnecting and restoring power may temporarily clear F34.
However, resetting the appliance cannot repair:
- Defective temperature sensor
- Damaged sensor wiring
- Loose connector
- Missing 5 VDC supply
- Persistent Cooktop System PCB circuit problem
If F34 returns, the rear induction temperature sensor circuit should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F34 repeatedly returns
- The rear induction burner does not operate correctly
- Sensor resistance requires testing
- The 5 VDC supply needs to be measured
- Internal wiring requires inspection
- The sensor tests normally but F34 continues
Testing inside an induction appliance can expose energized electrical components, so live electrical measurements should only be performed using appropriate safety procedures.
Key Point
F34 indicates a Rear Induction Burner Temperature Sensor Error.
The direct diagnostic information specifies:
Induction Temperature Sensor: 57 kΩ at 77°F
Cooktop System PCB: 5 VDC
The cause may be either a sensor problem or missing voltage from the main board. Therefore, the sensor, wiring, connections, and 5 VDC supply should be evaluated before identifying the failed component.
F36 — Inverter Board IGBT Error
The F36 error code indicates a failure involving the IGBT (Insulated Gate Bipolar Transistor) on the Inverter Board of an LG range or oven.
The IGBT is part of the inverter’s power electronics. It is responsible for controlling high-power electrical switching within the inverter system.
According to the direct LG diagnostic information, F36 is generated when the IGBT is defective. The specified repair is replacement of the Inverter Board.
What the F36 Error Code Means
LG identifies F36 as:
Inverter Board IGBT (Insulated Gate Bipolar Transistor) Error
The IGBT associated with this fault is located on the Inverter Board.
Unlike temperature sensor codes that may be caused by a sensor, wiring, connector, or missing reference voltage, F36 points directly toward an internal inverter-board power electronics failure.
The direct diagnostic information identifies the cause as:
Defective IGBT
and the specified solution as:
Replace Inverter Board
What Is an IGBT?
IGBT stands for:
Insulated Gate Bipolar Transistor
An IGBT is a semiconductor switching device used in high-power electronic circuits.
Within an inverter system, these devices rapidly control electrical power as part of the process used to operate the induction cooking system.
Because the IGBT is integrated into the Inverter Board, an IGBT failure is treated as an inverter-board-level fault rather than as a separate external sensor problem.
Common Cause
For F36, the direct source identifies one specific cause:
- Defective IGBT on the Inverter Board
The source does not list:
- A temperature sensor fault
- Missing 5 VDC sensor supply
- Burner sensor resistance problem
- Communication harness fault
- External power-supply problem
Those diagnostic paths belong to other induction-related error codes and should not automatically be applied to F36.
What You Can Check
There are limited user-level checks for F36 because the fault involves internal inverter electronics.
Useful observations include:
- Which induction cooking functions were operating when F36 appeared
- Whether an induction burner stopped working
- Whether the code appears immediately after attempting to use the cooktop
- Whether F36 returns after the appliance is restarted
- Whether other induction zones continue to operate
- The complete LG model number
These details can help identify the affected inverter configuration before service.
Why F36 Is Different From a Temperature Sensor Error
Several LG induction-related codes involve temperature sensors.
For example, F33 and F34 direct diagnosis toward burner temperature sensor circuits and provide specific sensor resistance and voltage references.
F36 is different.
It does not identify a burner temperature sensor circuit.
Instead, it identifies a fault involving the IGBT located on the Inverter Board.
Therefore, the 57 kΩ at 77°F and 5 VDC specifications used for F33 and F34 should not be applied to F36.
Why the Inverter Board Is Replaced
The direct diagnostic procedure specifies:
Replace Inverter Board
rather than replacing an individual IGBT.
The IGBT is part of the inverter’s electronic power-control circuitry. Repair procedures for the appliance treat the inverter as a board-level assembly.
Therefore, when the F36 diagnosis is confirmed, the published repair direction is replacement of the Inverter Board.
F36 vs. F33 and F34
F33, F34, and F36 can all involve an LG induction cooking system, but they identify different types of faults.
F33 — Front Induction Burner Temperature Sensor Error
→ Diagnose the front induction temperature sensor circuit.
F34 — Rear Induction Burner Temperature Sensor Error
→ Diagnose the rear induction temperature sensor circuit.
F36 — Inverter Board IGBT Error
→ Defective IGBT located on the Inverter Board.
This distinction is important because the diagnostic measurements used for the temperature sensors do not apply to an inverter IGBT fault.
F36 vs. CF5 and CF6
F36 is also closely related to CF5 and CF6.
CF5 → Left Inverter Board IGBT Error
CF6 → Right Inverter Board IGBT Error
F36 → Inverter Board IGBT Error
All three codes involve an IGBT on an Inverter Board.
However, CF5 and CF6 identify a specific left or right inverter location, while the F36 source describes the fault more generally as an Inverter Board IGBT Error.
The complete model number and the exact displayed error code should therefore be used when identifying the affected inverter board.
No Resistance or Voltage Specification Is Provided
The direct F36 diagnostic information does not provide an IGBT resistance, voltage, or current specification.
Therefore, values from other LG induction error codes should not be reused for F36.
In particular, do not apply:
- 57 kΩ at 77°F from induction temperature sensor codes
- 5 VDC from Cooktop System PCB sensor circuits
- Fan motor resistance values
- Door lock motor specifications
Any additional electrical measurements should come from service information for the exact LG model.
F36 Diagnostic Sequence
A practical diagnostic approach is:
F36 displayed
→ Confirm the exact error code
→ Record the complete LG model number
→ Confirm that the fault involves the induction/inverter system
→ Rule out incorrect code identification
→ Follow model-specific inverter diagnostics where applicable
→ Confirm the inverter-board-level fault
→ Replace the Inverter Board according to the published repair procedure
Because the direct source identifies a defective IGBT and specifies Inverter Board replacement, F36 has a much more direct diagnostic path than many sensor-related codes.
Can You Clear the F36 Code?
Disconnecting and restoring power may temporarily reset the electronic control and remove F36 from the display.
However, a power reset cannot repair a defective IGBT.
If F36 returns, the inverter system requires diagnosis.
Repeatedly resetting the appliance should not be considered a repair for a persistent inverter-board fault.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F36 repeatedly returns
- An induction burner does not operate
- The induction system stops working
- The Inverter Board requires inspection
- The inverter fault needs to be confirmed
- Inverter Board replacement is required
Induction inverter circuits involve high-power electronics and potentially hazardous electrical conditions. Internal diagnosis and board replacement should be performed using appropriate electrical safety procedures.
Key Point
F36 indicates an Inverter Board IGBT (Insulated Gate Bipolar Transistor) Error.
The direct LG diagnostic information states:
Cause: Defective IGBT
Location: Inverter Board
Solution: Replace Inverter Board.
Unlike F33 and F34, F36 is not an induction temperature sensor fault. The source provides no universal resistance or voltage specification for diagnosing the IGBT.
F38 — Communication Error Between Cooktop Main PCB & Inverter PCB
The F38 error code indicates a communication problem between the Cooktop Main PCB and the Inverter PCB in an LG range or oven.
These electronic boards must communicate with each other for the induction cooking system to operate correctly. If that communication is interrupted, the control may detect the fault and display F38.
What the F38 Error Code Means
LG identifies F38 as:
Communication Error Between Cooktop Main PCB & Inverter PCB
The direct diagnostic information identifies two primary causes:
- Loose connection at a connector
- PCB failure
This means F38 should not automatically be interpreted as a failed Inverter PCB.
A poor harness or connector connection can interrupt communication between otherwise functional electronic boards.
Common Causes
Diagnosis should focus on the communication path between the two PCBs.
Possible areas include:
- Loose harness connection
- Connector not fully seated
- Poor terminal contact
- Damaged communication wiring
- Cooktop Main PCB connection
- Inverter PCB connection
- Cooktop Main PCB failure
- Inverter PCB failure
The wiring and connections should be evaluated before determining that a PCB requires replacement.
What You Can Check
If F38 appears, note how the induction system behaves.
Useful observations include:
- Whether one or more induction burners stop operating
- Whether F38 appears immediately after power-up
- Whether the code appears only when a burner is activated
- Whether the burner LED indicator flashes
- Whether the error is intermittent
- Whether F38 returns after restarting the appliance
- Whether the cooktop was recently serviced
- The complete LG model number
An intermittent F38 can be particularly important because a loose or marginal connection may temporarily restore communication before failing again.
Check for a 3-Blink Burner LED Code
The direct F38 information provides an additional diagnostic clue:
The burner may show a 3-blink code on the burner LED indicator.
This indication may appear together with the communication fault.
If F38 is displayed, observe whether the burner LED also produces a repeating three-blink pattern.
This can provide additional evidence that the problem involves communication between the Cooktop Main PCB and Inverter PCB.
Check the Communication Harness
LG’s direct repair guidance begins with:
Check for poor connection of harness.
The harness connecting the electronic boards should therefore be inspected carefully.
Look for:
- Loose connector
- Connector not fully seated
- Bent terminal
- Backed-out terminal
- Broken wire
- Damaged insulation
- Heat-damaged connector
- Corrosion or contamination
- Poor electrical contact
A communication circuit can fail even when power is still available to both boards.
Check the Cooktop Main PCB Connection
Inspect the communication harness where it connects to the Cooktop Main PCB.
Make sure the connector is:
- Properly seated
- Mechanically secure
- Free from visible damage
- Making reliable terminal contact
A poor connection at the Main PCB can prevent data from reaching the Inverter PCB and produce F38 without either board necessarily being defective.
Check the Inverter PCB Connection
The opposite end of the communication path should also be inspected at the Inverter PCB.
The basic communication path can be represented as:
Cooktop Main PCB ↔ Harness / Connectors ↔ Inverter PCB
A fault anywhere along this path may interrupt board-to-board communication.
Both ends of the harness therefore need to be evaluated.
Harness Problem vs. PCB Failure
F38 has two broad diagnostic possibilities.
Communication path problem:
- Loose connector
- Poor harness connection
- Damaged wire
- Poor terminal contact
Electronic board problem:
- Cooktop Main PCB failure
- Inverter PCB failure
Because LG specifically instructs technicians to check for a poor harness connection, PCB replacement should not be the first conclusion based solely on the F38 code.
The communication path should be verified first.
What If the Harness Looks Normal?
A connector can appear properly installed while still having an electrical contact problem.
If the harness appears normal but F38 persists, further diagnosis may include checking:
- Connector terminal condition
- Wiring continuity
- Intermittent wiring faults
- Harness damage
- PCB-side connections
If the complete communication path is confirmed to be reliable, diagnosis may then move toward the electronic boards.
Model-specific service information should be used to determine which PCB is responsible.
F38 vs. F36
F36 and F38 both involve the induction inverter system, but they identify different types of faults.
F36 — Inverter Board IGBT Error
→ The direct source identifies a defective IGBT on the Inverter Board.
F38 — Communication Error Between Cooktop Main PCB & Inverter PCB
→ Communication between the two electronic boards has been interrupted.
Therefore:
F36 → Inverter power electronics fault
F38 → Board-to-board communication fault
The diagnostic paths should not be mixed.
F38 vs. CF7 and CF8
F38 is also closely related to CF7 and CF8.
CF7 → Communication Error Between Cooktop Main PCB & Left Inverter PCB
CF8 → Communication Error Between Cooktop Main PCB & Right Inverter PCB
F38 → Communication Error Between Cooktop Main PCB & Inverter PCB
The difference is that CF7 and CF8 identify a specific Left or Right Inverter PCB, while the F38 source refers more generally to the Inverter PCB.
All three codes direct attention to harness connections and possible PCB failure.
The complete LG model number should be used to identify the exact inverter configuration.
No Resistance or Voltage Specification Is Provided
The direct F38 page does not provide a resistance or voltage specification for the communication circuit.
Therefore, values from other induction codes should not be applied to F38.
In particular, do not reuse:
- 57 kΩ at 77°F from induction temperature sensors
- 5 VDC from temperature sensor circuits
- Fan motor specifications
- IGBT measurements from unrelated procedures
If electrical measurements beyond harness inspection are necessary, use service information for the exact LG model.
F38 Diagnostic Sequence
A practical diagnostic sequence is:
F38 displayed
→ Confirm the complete LG model number
→ Check for the 3-blink burner LED indication
→ Inspect the communication harness
→ Check the Cooktop Main PCB connector
→ Check the Inverter PCB connector
→ Inspect wiring and terminals for damage
→ Verify that the communication path is reliable
→ If the harness and connections are good, continue with model-specific PCB diagnosis
→ Replace the appropriate PCB only after the fault has been properly isolated
This sequence follows LG’s published direction to check the harness before moving toward PCB replacement.
Can You Clear the F38 Code?
Disconnecting and restoring power may temporarily clear F38 if communication is restored.
However, resetting the appliance cannot repair:
- Loose connector
- Damaged communication harness
- Poor terminal contact
- Persistent PCB failure
If F38 returns, the communication circuit should be diagnosed.
An intermittent code should not be ignored because a marginal connector or wiring problem may temporarily reconnect after power cycling.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F38 repeatedly returns
- Induction burners stop operating
- The burner LED shows a 3-blink indication
- Internal harness connections require inspection
- Wiring continuity needs to be tested
- Harness connections appear normal but communication still fails
- PCB diagnosis or replacement is required
Induction appliances contain high-power electronic circuits, so internal electrical diagnosis should be performed using appropriate electrical safety procedures.
Key Point
F38 indicates a Communication Error Between the Cooktop Main PCB and Inverter PCB.
The direct LG information specifies:
Cause: Loose connector connection or PCB failure
Additional indication: Burner may display a 3-blink LED code
Solution: Check for a poor harness connection or replace the appropriate PCB.
F38 does not automatically mean the Inverter PCB has failed. The harness and connectors between the boards should be checked before determining that PCB replacement is necessary.
F4 — Lower Oven Thermistor Error
The F4 error code indicates a problem with the Lower Oven Thermistor circuit in an LG range or oven.
The lower oven uses a temperature sensor, or thermistor, to provide temperature information to the Main PCB. If the control does not receive the expected signal from the Lower Oven Sensor, it may display F4.
What the F4 Error Code Means
LG identifies F4 as:
Lower Oven Thermistor Error
The direct diagnostic information describes the cause as:
No signal to Main PCB from the Lower Oven Sensor.
This means F4 is fundamentally a temperature sensor signal problem.
The diagnostic path should focus on the complete sensor circuit:
Lower Oven Sensor → Wiring / Connections → Main PCB
The code does not automatically prove that the Lower Oven Sensor itself has failed.
Common Causes
Possible areas requiring inspection include:
- Lower Oven Sensor
- Lower Oven Sensor connector
- Sensor wiring
- Loose electrical connection
- Broken wire
- Damaged wiring
- Poor terminal contact
- Main PCB connector
- Sensor signal path to the Main PCB
Because the defining condition is a missing sensor signal, any interruption between the sensor and Main PCB may potentially produce F4.
What You Can Check
If F4 appears, record how the lower oven behaves.
Useful observations include:
- Whether F4 appears immediately after power-up
- Whether the code appears when the lower oven is turned on
- Whether the oven begins heating before the code appears
- Whether temperature regulation appears abnormal
- Whether the code is intermittent or persistent
- Whether the appliance was recently serviced
- Whether the Lower Oven Sensor or related wiring was recently disturbed
- The complete LG model number
These observations can help determine whether the sensor signal is completely absent or the problem is intermittent.
Check the Lower Oven Sensor Connections
The direct F4 troubleshooting procedure specifically instructs technicians to check the:
Lower Oven Sensor connections.
Inspect the sensor-side circuit for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat-damaged connection
- Poor electrical contact
A functional temperature sensor cannot provide useful information to the Main PCB if its electrical connection is interrupted.
Check the Main PCB Connections
LG also specifically instructs technicians to check the:
Main PCB connections.
The Main PCB must receive the temperature sensor signal to monitor and regulate lower oven temperature.
The basic signal path is:
Lower Oven Sensor → Sensor Wiring → Connectors → Main PCB
A poor connection at the Main PCB can therefore produce the same missing-signal condition as a problem at the sensor itself.
Both ends of the circuit should be inspected before identifying a failed component.
Sensor vs. Wiring Problem
F4 should not immediately be interpreted as a defective Lower Oven Sensor.
Because the control is reporting that it is not receiving the sensor signal, diagnosis should distinguish between:
Sensor problem
- Failed or electrically abnormal Lower Oven Sensor
Circuit problem
- Loose connector
- Broken wire
- Damaged harness
- Poor terminal contact
- Main PCB connection problem
The complete signal path should be checked before replacing the sensor.
What If the Connections Look Normal?
If the Lower Oven Sensor and Main PCB connections appear normal but F4 continues, further electrical diagnosis may be necessary.
A technician may need to evaluate:
- Lower Oven Sensor electrically
- Wiring continuity
- Connector terminal contact
- Intermittent open circuit
- Harness condition
- Main PCB sensor input circuit
The exact testing procedure should be based on service information for the specific LG model.
No Resistance Specification Is Provided for F4
The direct F4 page does not provide a specific resistance value for the Lower Oven Sensor.
It also does not provide a voltage specification.
Therefore, resistance or voltage values from other LG oven codes should not automatically be applied to F4.
If the Lower Oven Sensor requires electrical testing, use the specifications provided for the exact LG model.
This is especially important because sensor specifications and diagnostic procedures may vary between appliance designs.
Why the Lower Oven Sensor Matters
The Lower Oven Sensor provides temperature feedback that allows the electronic control to regulate heating.
The Main PCB uses this information to determine when heating components should operate and when the desired oven temperature has been reached.
Without a valid temperature signal, accurate temperature control may not be possible.
F4 therefore protects against operating the lower oven when the control cannot reliably determine oven temperature.
F4 vs. F16
F4 and F16 both involve lower oven temperature, but they identify different conditions.
F4 — Lower Oven Thermistor Error
→ No signal to the Main PCB from the Lower Oven Sensor.
F16 — Lower Oven Too Hot
→ Lower oven temperature exceeds 650°F continuously for more than two minutes, except during Self Clean.
Therefore:
F4 → Sensor signal problem
F16 → Over-temperature condition
The diagnostic paths should not be mixed.
F4 vs. F25
F4 should also be distinguished from F25.
F4 — Lower Oven Thermistor Error
→ The Main PCB is not receiving the Lower Oven Sensor signal.
F25 — Lower Oven Heating Error
→ The lower oven does not exceed 150°F within five minutes after preheating begins.
F4 directs diagnosis primarily toward the temperature sensor signal circuit.
F25 directs diagnosis primarily toward the lower oven heating system.
F4 Diagnostic Sequence
A practical diagnostic sequence is:
F4 displayed
→ Confirm the complete LG model number
→ Identify the Lower Oven Sensor circuit
→ Inspect the Lower Oven Sensor connection
→ Inspect sensor wiring and harness
→ Check the Main PCB connection
→ Look for loose, damaged, or interrupted connections
→ Test the sensor and wiring according to model-specific specifications
→ If the sensor and wiring test correctly, continue with control-side diagnosis
The goal is to determine why the Main PCB is not receiving the expected signal from the Lower Oven Sensor.
Can You Clear the F4 Code?
Disconnecting and restoring power may temporarily reset the electronic control and clear F4 from the display.
However, a reset cannot repair:
- Failed Lower Oven Sensor
- Broken sensor wiring
- Loose connector
- Damaged harness
- Poor Main PCB connection
- Persistent sensor circuit problem
If F4 returns, the Lower Oven Sensor circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F4 repeatedly returns
- The lower oven does not operate normally
- Temperature regulation is abnormal
- Internal sensor wiring requires inspection
- The Lower Oven Sensor requires electrical testing
- Sensor and PCB connections appear normal but F4 continues
A technician can isolate the sensor circuit, inspect wiring continuity, test the Lower Oven Sensor according to the model-specific specification, and determine whether the fault is in the sensor, wiring, connections, or control side.
Key Point
F4 indicates a Lower Oven Thermistor Error.
The direct LG diagnostic information states:
Cause: No signal to Main PCB from the Lower Oven Sensor
Solution: Check Main PCB connections and Lower Oven Sensor connections.
F4 does not automatically mean that the Lower Oven Sensor itself has failed. The sensor, wiring, connectors, and Main PCB connections should be evaluated as a complete signal circuit.
F42 — Over Voltage Error
The F42 error code indicates that an LG range or oven has detected an over-voltage condition in the incoming household electrical supply.
Unlike many appliance error codes that point toward an internal sensor, heating component, or control circuit, F42 directs attention primarily to the power being supplied to the appliance.
What the F42 Error Code Means
LG identifies F42 as:
Over Voltage Error
The direct diagnostic information identifies the cause as:
Voltage from the customer’s house is too high.
The recommended solution is to have an electrician check the household power supply.
This means F42 should not automatically be interpreted as an appliance component failure.
Common Cause
The direct F42 information identifies one primary cause:
- Household supply voltage is too high
The source does not identify a temperature sensor, heating element, inverter board, or Main PCB as the primary cause of F42.
Diagnosis should therefore begin with the electrical supply rather than replacing internal appliance components.
What You Can Check
If F42 appears, useful observations include:
- Whether the code appeared after a power interruption
- Whether there was a recent electrical problem in the home
- Whether lights or other appliances have behaved unusually
- Whether electrical work was recently performed
- Whether F42 appears immediately when the appliance is powered
- Whether the code returns after power is restored
- The complete LG model number
Do not repeatedly operate the appliance if an abnormal household voltage condition is suspected.
Check the Household Electrical Supply
The primary diagnostic direction for F42 is the incoming electrical supply.
A qualified electrician can verify whether the voltage being supplied to the appliance is appropriate for the installation and appliance specification.
This may involve checking:
- Supply voltage
- Electrical panel
- Circuit supplying the range or oven
- Wiring connections
- Electrical service conditions
The exact testing procedure depends on the installation and should be performed using appropriate electrical safety procedures.
Why an Over-Voltage Condition Matters
Electronic controls and other electrical components are designed to operate within specified electrical conditions.
If incoming voltage is excessively high, components may be exposed to electrical stress outside their intended operating conditions.
F42 therefore should not simply be cleared and ignored if it repeatedly returns.
The underlying electrical supply condition should be investigated.
F42 Does Not Automatically Mean the Main PCB Has Failed
Because F42 appears on the appliance display, it may be tempting to assume that the electronic control itself has failed.
However, the direct F42 diagnostic information specifically points toward:
Household voltage being too high.
Therefore, replacing the Main PCB without first checking the electrical supply could leave the actual cause unresolved.
The household power supply should be evaluated first.
Do Not Assume a Universal Voltage Threshold
The direct F42 source does not specify an exact voltage threshold that triggers the code.
Therefore, a universal acceptable voltage range should not be assigned to F42 based solely on this error-code page.
The correct electrical requirements should be confirmed using:
- Appliance rating information
- Installation instructions
- Model-specific service documentation
- Appropriate electrical standards for the installation
This is especially important because LG ranges and ovens can have different electrical configurations.
F42 vs. CFC
F42 is closely related to the previously covered CFC code.
CFC — Over Voltage Error
→ Household voltage is too high.
F42 — Over Voltage Error
→ Household voltage is too high.
For both codes, the published diagnostic direction is to have the household electrical supply checked by an electrician.
The different codes may be used by different LG models or electronic control configurations.
The exact displayed code and complete model number should therefore be recorded before diagnosis.
Appliance Problem vs. Household Power Problem
F42 is important because it changes the normal troubleshooting direction.
For many error codes, diagnosis begins inside the appliance:
Sensor → Wiring → PCB
For F42, the initial direction is:
Household Electrical Supply → Appliance
This distinction can prevent unnecessary replacement of appliance components when the actual problem originates outside the range or oven.
F42 Diagnostic Sequence
A practical diagnostic sequence is:
F42 displayed
→ Record the complete LG model number
→ Stop repeatedly resetting the appliance
→ Consider whether a recent electrical disturbance occurred
→ Have the incoming household power checked
→ Compare the measured supply with the requirements for the specific appliance
→ Correct any abnormal electrical supply condition
→ Confirm normal appliance operation afterward
→ If F42 continues despite verified correct power, proceed with model-specific appliance diagnosis
The household electrical supply should be verified before internal components are blamed for the error.
Can You Clear the F42 Code?
Disconnecting and restoring power may temporarily remove F42 from the display.
However, resetting the appliance cannot correct an actual over-voltage condition.
If the incoming voltage remains too high, the code may return and the appliance may continue to be exposed to abnormal electrical conditions.
The underlying supply problem should be corrected instead of repeatedly resetting the range or oven.
When Professional Diagnosis Is Recommended
Because F42 specifically involves household electrical power, the direct recommendation is to have an electrician check the house power.
Professional electrical inspection is particularly appropriate when:
- F42 repeatedly returns
- Other electrical equipment behaves abnormally
- A recent power or electrical-service problem occurred
- Supply voltage needs to be measured
- Panel or circuit wiring requires inspection
- The appliance cannot be operated normally
Testing mains voltage can expose hazardous electrical conditions and should be performed by a qualified person.
Key Point
F42 indicates an Over Voltage Error.
The direct LG diagnostic information states:
Cause: Household voltage is too high
Solution: Have an electrician check the house power.
F42 should therefore be treated first as a power-supply problem, not automatically as a failed appliance component.
F45 — Box Fan Error
The F45 error code indicates a problem with the Box Fan system in an LG range or oven.
The Box Fan is part of the cooktop’s cooling system. If the fan motor is defective or the motor is not receiving the required 12 VDC supply, the appliance may detect abnormal fan operation and display F45.
What the F45 Error Code Means
LG identifies F45 as:
Box Fan Error
The direct diagnostic information identifies two primary possibilities:
- The fan motor is defective
- The fan motor is missing 12 VDC
This means F45 does not automatically confirm that the Box Fan motor has failed.
The complete fan circuit should be considered:
Cooktop System PCB → Wiring / Connections → Box Fan Motor
Diagnosis should determine whether the motor itself is defective or whether it is not receiving the required electrical supply.
Common Causes
Possible areas requiring inspection include:
- Box Fan motor
- Box Fan motor winding
- Fan electrical connector
- Wiring between the fan and Cooktop System PCB
- Loose electrical connection
- Damaged wiring
- Poor terminal contact
- Missing 12 VDC supply
- Cooktop System PCB fan circuit
Because missing voltage can produce the same error as a defective motor, the electrical supply should be checked before concluding that the fan needs replacement.
What You Can Check
If F45 appears, note how the appliance behaves.
Useful observations include:
- Whether the Box Fan can be heard operating
- Whether the fan starts and then stops
- Whether unusual fan noises are present
- Whether F45 appears immediately or after cooktop operation begins
- Whether induction burners continue operating normally
- Whether the error returns after restarting the appliance
- Whether the cooktop was recently serviced
- The complete LG model number
Abnormal noises such as humming, scraping, or rattling may provide additional clues about the condition of the fan.
Check the Box Fan for Mechanical Problems
Before electrical testing, the fan should be inspected for obvious mechanical problems with the appliance safely disconnected from power.
Possible issues include:
- Fan blade obstruction
- Debris around the fan
- Damaged fan blade
- Fan blade contacting another component
- Motor unable to rotate normally
- Mechanical binding
A mechanically restricted fan may not operate correctly even if its electrical circuit is functional.
Check for 12 VDC From the Cooktop System PCB
The direct F45 diagnostic information provides a specific voltage check:
12 VDC from the Cooktop System PCB.
This measurement helps determine whether the Box Fan is receiving the electrical supply expected by the system.
The basic diagnostic logic is:
12 VDC present but fan does not operate correctly
→ Investigate the Box Fan motor and its immediate connections.
12 VDC missing when the fan should be operating
→ Investigate wiring, connectors, and the Cooktop System PCB side of the circuit.
Because this measurement may require testing an energized appliance, it should only be performed using appropriate electrical safety procedures.
Check the Box Fan Motor Winding
LG also provides a specific motor winding value for F45:
4.1 MΩ
This provides an additional diagnostic reference for evaluating the Box Fan motor.
A technician can measure the fan motor winding and compare the result with the published 4.1 MΩ specification.
A substantially abnormal reading may indicate a problem with the fan motor winding.
Resistance testing should be performed with power disconnected from the appliance.
Check the Fan Wiring and Connections
The electrical path between the Cooktop System PCB and Box Fan should also be inspected.
Look for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat-damaged connector
- Poor electrical contact
A functional Box Fan cannot operate normally if its 12 VDC supply is interrupted by a wiring or connector problem.
Fan Motor vs. Power Supply Diagnosis
F45 provides two useful diagnostic reference points:
Box Fan Motor Winding: 4.1 MΩ
Cooktop System PCB Supply: 12 VDC
These values help separate the motor side from the supply side.
A simplified diagnostic path is:
Cooktop System PCB (12 VDC) → Wiring / Connector → Box Fan Motor (4.1 MΩ winding)
If the motor winding is abnormal, investigate the Box Fan motor.
If the winding appears correct but the required 12 VDC is missing, diagnosis should move toward the wiring, connectors, and Cooktop System PCB.
What If Both Measurements Are Correct?
If the fan motor winding measures approximately 4.1 MΩ and the expected 12 VDC is present when the fan should operate, further diagnosis may be necessary.
Inspect:
- Fan connector contact
- Wiring integrity
- Intermittent connections
- Mechanical fan operation
- Fan assembly
- Cooktop System PCB connector
The complete model number should be used for additional model-specific diagnosis.
F45 vs. CFF
F45 is especially interesting because its published diagnostic information closely matches the previously covered CFFcode.
CFF — Box Fan Error
→ Fan motor may be defective or missing 12 VDC
→ Check 12 VDC from Cooktop System PCB
→ Check fan motor winding for 4.1 MΩ
F45 — Box Fan Error
→ Fan motor may be defective or missing 12 VDC
→ Check 12 VDC from Cooktop System PCB
→ Check fan motor winding for 4.1 MΩ
The two codes may be used by different LG models or control configurations.
They should remain separate entries in the error-code guide even though their published diagnostic procedures overlap.
F45 vs. CFE
F45 should not be confused with CFE — Blower Fan Error.
CFE → Blower Fan Error
→ Check 12 VDC from Cooktop Inverter PCB
F45 → Box Fan Error
→ Check 12 VDC from Cooktop System PCB
→ Check motor winding for 4.1 MΩ
The PCB supplying the fan is an important distinction.
For F45, the source specifically identifies the:
Cooktop System PCB
F45 Diagnostic Sequence
A practical diagnostic sequence is:
F45 displayed
→ Confirm the complete LG model number
→ Identify the Box Fan
→ Check for mechanical obstruction or abnormal fan movement
→ Inspect fan wiring and connectors
→ Check for 12 VDC from the Cooktop System PCB
→ Measure Box Fan motor winding resistance
→ Compare with 4.1 MΩ
→ If voltage is present but the motor does not operate correctly, investigate the fan motor
→ If voltage is missing, investigate wiring, connectors, and the PCB side
→ Continue with model-specific diagnosis if necessary
This sequence helps distinguish between a fan motor fault and a missing supply-voltage problem.
Can You Clear the F45 Code?
Disconnecting and restoring power may temporarily clear F45.
However, resetting the appliance cannot repair:
- Defective Box Fan motor
- Abnormal motor winding
- Damaged wiring
- Loose connector
- Missing 12 VDC supply
- Persistent Cooktop System PCB circuit problem
If F45 returns, the Box Fan system should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F45 repeatedly returns
- The Box Fan does not operate
- The fan makes abnormal noises
- The 4.1 MΩ motor winding needs to be checked
- The 12 VDC supply requires testing
- Internal wiring requires inspection
- The fan tests normally but F45 continues
Live electrical measurements inside the appliance should only be performed using appropriate electrical safety procedures.
Key Point
F45 indicates a Box Fan Error.
The direct diagnostic information provides two important specifications:
Cooktop System PCB output: 12 VDC
Box Fan motor winding: 4.1 MΩ
The fan motor may be defective, or the required 12 VDC supply may be missing. Therefore, both the Box Fan motor and its power-supply circuit should be evaluated before identifying the failed component.
F46 — IH (Induction Heater) Blow Fan Error
The F46 error code indicates a problem with the IH (Induction Heater) Blow Fan system in an LG range or oven.
The induction system uses a fan to provide airflow for cooling components associated with the induction heating system. If the fan motor is defective or the required electrical supply is missing, the appliance may detect abnormal fan operation and display F46.
What the F46 Error Code Means
LG identifies F46 as:
IH (Induction Heater) Blow Fan Error
The direct diagnostic information identifies two primary possibilities:
- The fan motor is defective
- The fan motor is missing 12 VDC
The published diagnostic procedure therefore evaluates both the fan motor and the electrical supply from the Cooktop System PCB.
F46 does not automatically mean that the fan motor itself has failed.
Common Causes
Possible areas requiring inspection include:
- IH Blow Fan motor
- Fan motor winding
- Fan electrical connector
- Wiring between the fan and Cooktop System PCB
- Loose connector
- Damaged wiring
- Poor terminal contact
- Missing 12 VDC supply
- Cooktop System PCB fan circuit
The diagnostic goal is to determine whether the fan itself is defective or whether it cannot operate because the required electrical supply is missing.
What You Can Check
If F46 appears, note how the induction system behaves.
Useful observations include:
- Whether the fan can be heard operating
- Whether the fan starts and then stops
- Whether unusual fan noises are present
- Whether F46 appears when an induction burner is used
- Whether induction cooking stops or becomes unavailable
- Whether F46 returns after restarting the appliance
- Whether the appliance was recently serviced
- The complete LG model number
Sounds such as humming, scraping, rattling, or repeated attempts to start may provide useful information about the fan’s mechanical condition.
Check the IH Blow Fan for Mechanical Problems
With the appliance safely disconnected from power, the fan assembly can be inspected for obvious mechanical problems.
Possible conditions include:
- Debris obstructing the fan
- Fan blade interference
- Damaged fan blade
- Mechanical binding
- Fan unable to rotate normally
- Physical damage to the fan assembly
A mechanically restricted fan may fail to provide the expected airflow even when its electrical circuit is functional.
Check for 12 VDC From the Cooktop System PCB
The direct F46 diagnostic information specifies:
Check for 12 VDC from the Cooktop System PCB.
This measurement helps determine whether the fan is receiving the electrical supply expected by the system.
The basic diagnostic logic is:
12 VDC present but fan does not operate correctly
→ Investigate the IH Blow Fan motor and its immediate connections.
12 VDC missing when the fan should be operating
→ Investigate the wiring, connectors, and Cooktop System PCB side of the circuit.
Because checking this voltage may require testing an energized appliance, live electrical measurements should only be performed by someone qualified to work safely around energized equipment.
Check the Fan Motor Winding
LG also provides a specific winding specification:
Fan motor winding: 4.1 MΩ
This provides a second diagnostic reference for evaluating the IH Blow Fan motor.
Resistance testing should be performed with the appliance disconnected from electrical power.
A reading substantially inconsistent with the published specification may indicate a problem with the fan motor winding.
Check the Wiring and Connections
The electrical path between the Cooktop System PCB and the fan should also be inspected.
Look for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat-damaged connector
- Poor electrical contact
A functional fan cannot operate normally if the required 12 VDC supply is interrupted somewhere between the Cooktop System PCB and fan motor.
Fan Motor vs. Power Supply Diagnosis
F46 provides two useful diagnostic reference points:
IH Blow Fan Motor Winding: 4.1 MΩ
Cooktop System PCB Supply: 12 VDC
A simplified diagnostic path is:
Cooktop System PCB (12 VDC) → Wiring / Connector → IH Blow Fan Motor (4.1 MΩ winding)
If the fan motor winding is outside specification, the motor becomes the primary area of investigation.
If the winding appears correct but 12 VDC is missing, diagnosis should move toward the wiring, connections, and Cooktop System PCB.
What If Both Measurements Are Correct?
If approximately 4.1 MΩ is measured at the fan motor winding and the expected 12 VDC is available when the fan should operate, further diagnosis may be required.
Check:
- Mechanical fan operation
- Fan connector contact
- Harness condition
- Intermittent wiring problems
- Cooktop System PCB connector
The service information for the exact LG model should be used if the published basic checks do not identify the cause.
F45 vs. F46
F45 and F46 are closely related fan-system codes, but their titles identify different fan functions.
F45 — Box Fan Error
F46 — IH (Induction Heater) Blow Fan Error
Interestingly, the direct diagnostic specifications are the same for both:
12 VDC from Cooktop System PCB
4.1 MΩ fan motor winding
The exact error code should therefore be used to identify which fan system requires diagnosis.
F46 vs. CFE and CFF
Several LG induction-related codes involve cooling fans, but they should not be treated as interchangeable.
CFE — Blower Fan Error
→ Check 12 VDC from Cooktop Inverter PCB
→ Direct source does not provide the 4.1 MΩ winding specification.
CFF — Box Fan Error
→ Check 12 VDC from Cooktop System PCB
→ Fan motor winding: 4.1 MΩ
F46 — IH Blow Fan Error
→ Check 12 VDC from Cooktop System PCB
→ Fan motor winding: 4.1 MΩ
The PCB identified as the voltage source is therefore an important diagnostic distinction.
F46 Diagnostic Sequence
A practical diagnostic sequence is:
F46 displayed
→ Confirm the complete LG model number
→ Identify the IH Blow Fan
→ Check for obvious mechanical obstruction
→ Inspect fan wiring and connectors
→ Measure fan motor winding resistance
→ Compare with 4.1 MΩ
→ Check for 12 VDC from the Cooktop System PCB when appropriate
→ If voltage is present but the fan does not operate correctly, investigate the fan motor
→ If voltage is missing, investigate wiring, connections, and the PCB side
→ Continue with model-specific diagnosis if necessary
This sequence helps distinguish between a fan motor problem and a missing power-supply condition.
Can You Clear the F46 Code?
Disconnecting and restoring power may temporarily clear F46.
However, a reset cannot repair:
- Defective fan motor
- Abnormal fan motor winding
- Mechanical fan problem
- Damaged wiring
- Loose connector
- Missing 12 VDC supply
- Persistent Cooktop System PCB circuit problem
If F46 returns, the IH Blow Fan circuit should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F46 repeatedly returns
- The IH Blow Fan does not operate
- The fan makes abnormal noises
- Fan motor resistance needs to be measured
- The 12 VDC supply requires testing
- Internal wiring requires inspection
- The fan tests normally but F46 continues
Induction cooking appliances contain high-power electronic components. Internal diagnosis and live electrical measurements should be performed using appropriate electrical safety procedures.
Key Point
F46 indicates an IH (Induction Heater) Blow Fan Error.
The direct diagnostic information specifies:
Cause: Fan motor is defective or missing 12 VDC
Supply: 12 VDC from Cooktop System PCB
Fan motor winding: 4.1 MΩ
F46 does not automatically prove that the fan motor has failed. Both the fan motor and its 12 VDC supply circuitshould be evaluated before identifying the failed component.
F5 — Lower Oven Thermistor Error
The F5 error code usually indicates a problem with the Lower Oven Thermistor circuit in an LG range or oven.
The Lower Oven Sensor provides temperature information to the Main PCB. If the electronic control does not receive the expected signal from this sensor, the appliance may display F5.
However, there is an important model-specific exception: on the LG Electric Range LRE30757, F5 indicates a Warming Drawer Sensor Shorted condition instead.
What the F5 Error Code Means
For most LG ranges and ovens:
F5 = Lower Oven Thermistor Error
The defining condition is that the Main PCB is not receiving a signal from the Lower Oven Sensor.
The diagnostic path should therefore focus on:
Lower Oven Sensor → Wiring / Connections → Main PCB
A missing sensor signal does not automatically mean the sensor itself has failed. A wiring, connector, or connection problem can interrupt the same signal.
Important Model Exception — LRE30757
The LG Electric Range LRE30757 uses F5 differently.
For this specific model:
F5 = Warming Drawer Sensor Shorted
This is a completely different diagnostic condition from the Lower Oven Thermistor Error used by other models.
Therefore, always confirm the complete model number before troubleshooting F5.
LRE30757
→ Warming Drawer Sensor Shorted
All other models covered by this diagnostic information
→ Lower Oven Thermistor Error
Common Causes
For models where F5 means Lower Oven Thermistor Error, possible areas requiring inspection include:
- Lower Oven Sensor
- Lower Oven Sensor connector
- Sensor wiring
- Loose electrical connection
- Broken conductor
- Damaged wiring
- Poor terminal contact
- Main PCB connection
- Interrupted sensor signal circuit
Because F5 is defined by the absence of a sensor signal, the entire circuit between the sensor and Main PCB should be evaluated.
What You Can Check
If F5 appears, record how the appliance behaves.
Useful observations include:
- Whether F5 appears immediately after power-up
- Whether it appears when the lower oven is started
- Whether the lower oven begins heating
- Whether temperature regulation appears abnormal
- Whether F5 is intermittent or persistent
- Whether the appliance was recently serviced
- Whether sensor wiring was recently disturbed
- The complete LG model number
Checking the model number first is particularly important for F5 because of the LRE30757 exception.
Check the Lower Oven Sensor Connections
For the standard F5 condition, the direct diagnostic procedure specifically says to check the:
Lower Oven Sensor connections.
Inspect the sensor-side circuit for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat-damaged connector
- Poor electrical contact
A functional thermistor cannot provide temperature information if its electrical path to the control is interrupted.
Check the Main PCB Connections
The direct F5 troubleshooting information also instructs technicians to check the:
Main PCB connections.
The Main PCB depends on the Lower Oven Sensor signal to determine oven temperature.
The basic signal path is:
Lower Oven Sensor → Sensor Wiring → Connectors → Main PCB
A connection problem at either end can result in the same missing-signal condition.
Sensor vs. Wiring Problem
F5 should not automatically lead to replacement of the Lower Oven Sensor.
Diagnosis should distinguish between:
Sensor problem
- Electrically failed or abnormal Lower Oven Sensor
Circuit problem
- Loose connector
- Broken wire
- Damaged harness
- Poor terminal contact
- Main PCB connection problem
The complete signal path should be checked before determining which component requires repair.
What If the Connections Look Normal?
If the Lower Oven Sensor and Main PCB connections appear normal but F5 continues, further model-specific electrical diagnosis may be required.
A technician may need to evaluate:
- Lower Oven Sensor
- Wiring continuity
- Harness condition
- Connector terminal contact
- Intermittent open circuit
- Main PCB sensor input circuit
The exact electrical specifications should come from service information for the specific LG model.
No Resistance or Voltage Specification Is Provided
The direct F5 page does not provide a specific resistance or voltage value for the Lower Oven Sensor.
Therefore, specifications from other LG temperature-sensor codes should not automatically be applied to F5.
If resistance testing is required, use the service documentation for the exact appliance model.
This is especially important because F5 itself already demonstrates that LG can assign different diagnostic meanings to the same code depending on the model.
Why the Lower Oven Thermistor Matters
The Lower Oven Sensor provides temperature feedback to the electronic control.
The Main PCB uses this information to regulate the oven’s heating system and maintain the selected cooking temperature.
If the sensor signal disappears, the control can no longer reliably determine the lower oven temperature.
F5 therefore identifies a problem in an important temperature-feedback circuit.
F4 vs. F5
The published descriptions of F4 and F5 are notably similar.
F4 — Lower Oven Thermistor Error
→ No signal to Main PCB from the Lower Oven Sensor.
F5 — Lower Oven Thermistor Error
→ No signal to Main PCB from the Lower Oven Sensor for most models.
However, F5 has the additional model-specific exception:
LRE30757 → Warming Drawer Sensor Shorted
Because LG can use codes differently between model families, F4 and F5 should remain separate entries in the error-code guide.
F5 Diagnostic Sequence
For most models:
F5 displayed
→ Confirm the complete model number
→ Determine whether the appliance is LRE30757
→ If not, identify the Lower Oven Sensor circuit
→ Check the Lower Oven Sensor connections
→ Inspect sensor wiring and harness
→ Check Main PCB connections
→ Look for an interrupted sensor signal path
→ Continue with model-specific sensor testing if necessary
For LRE30757, do not use the standard Lower Oven Thermistor diagnostic path:
F5 → Warming Drawer Sensor Shorted
The warming drawer sensor circuit should be diagnosed according to the service information for that model.
Can You Clear the F5 Code?
Disconnecting and restoring power may temporarily clear F5.
However, a reset cannot repair:
- Failed temperature sensor
- Broken sensor wiring
- Loose connector
- Damaged harness
- Persistent Main PCB connection problem
- Shorted Warming Drawer Sensor on LRE30757
If F5 returns, the appropriate sensor circuit should be diagnosed according to the model.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F5 repeatedly returns
- The lower oven does not operate normally
- Temperature regulation is abnormal
- Sensor wiring requires inspection
- Electrical sensor testing is necessary
- Connections appear normal but the error continues
- The appliance is an LRE30757 with the Warming Drawer Sensor Shorted condition
A technician can identify the correct circuit from the model number and determine whether the fault originates with the sensor, wiring, connectors, or control side.
Key Point
For most LG ranges and ovens:
F5 = Lower Oven Thermistor Error
Cause: No signal to Main PCB from the Lower Oven Sensor
Initial checks: Main PCB connections and Lower Oven Sensor connections.
But there is an important exception:
LG Electric Range LRE30757 → F5 = Warming Drawer Sensor Shorted.
Always confirm the model number before diagnosing F5.
F51 — Griddle Sensor Open Error
The F51 error code indicates an open circuit condition in the Griddle Sensor of an LG range or oven.
The griddle temperature sensor provides temperature information used by the appliance’s electronic control system. If the sensor circuit becomes electrically open, the control can no longer receive the expected temperature-dependent signal and may display F51.
What the F51 Error Code Means
LG identifies F51 as:
Griddle Sensor Open Error
The direct diagnostic procedure is straightforward:
Check Griddle Sensor
If the sensor reads open resistance, the specified solution is:
Replace sensor.
This makes F51 specifically an open-circuit griddle sensor fault.
What Is an Open Sensor Circuit?
An electrical sensor circuit must provide a continuous path through which its resistance can be measured.
An open circuit means that electrical continuity through that path has been interrupted.
For a temperature sensor circuit, an open condition can prevent the electronic control from receiving usable temperature information.
An open reading may therefore indicate that the Griddle Sensor itself is no longer electrically continuous.
Common Causes
The direct F51 source specifically directs diagnosis toward the Griddle Sensor.
Possible areas associated with an open sensor circuit can include:
- Open Griddle Sensor
- Sensor connection
- Sensor wiring
- Broken conductor
- Loose connector
- Damaged terminal
However, the published F51 procedure specifically says that if the sensor itself reads open resistance, replace the sensor.
What You Can Check
If F51 appears, record the circumstances surrounding the error.
Useful information includes:
- Whether the error appears when using the griddle
- Whether the griddle heats normally
- Whether F51 appears immediately
- Whether the code is intermittent or persistent
- Whether the appliance was recently serviced
- Whether wiring near the griddle sensor was disturbed
- The complete LG model number
These observations can provide useful context before electrical testing begins.
Check the Griddle Sensor
The primary F51 diagnostic step is to check the:
Griddle Sensor
The sensor should be electrically evaluated to determine whether it has an open circuit.
If testing directly across the sensor shows open resistance, the direct source specifies replacement of the sensor.
Resistance testing should be performed with the appliance safely disconnected from electrical power.
Check the Sensor Connections
Although the direct F51 page focuses on testing the sensor itself, the sensor’s physical connections are also relevant when investigating an apparent open circuit.
Inspect for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Poor electrical contact
This can help distinguish an electrically open sensor from an interruption elsewhere in the sensor circuit.
Sensor vs. Wiring Diagnosis
A useful distinction is whether the sensor itself reads open or whether the complete circuit appears open because of another interruption.
Testing directly at the Griddle Sensor helps isolate these possibilities.
Sensor itself reads open
→ The direct F51 procedure specifies replace the sensor.
Sensor itself has continuity but the circuit still produces F51
→ Further inspection of wiring, connectors, and the model-specific sensor circuit may be necessary.
This approach avoids replacing a sensor based only on the displayed code without confirming the electrical condition.
No Specific Resistance Value Is Provided
The direct F51 page does not provide a normal resistance specification for the Griddle Sensor.
It only specifies that:
If the sensor reads open resistance → replace sensor.
Therefore, resistance values from other LG temperature sensors should not be applied to F51.
Do not reuse specifications such as:
- 57 kΩ from induction burner sensors
- 1.09 kΩ from steam sensors
- Lower oven thermistor values
- Other unrelated sensor specifications
If a precise normal resistance range is required, use service information for the exact LG model.
Why the Griddle Sensor Matters
Temperature sensors allow the electronic control to monitor thermal conditions and regulate operation.
If the Griddle Sensor becomes electrically open, the control loses the temperature information expected from that sensor circuit.
Continuing normal temperature regulation may therefore become unreliable, which is why the control can generate F51 when the open condition is detected.
F51 Diagnostic Sequence
A practical diagnostic sequence is:
F51 displayed
→ Confirm the complete LG model number
→ Identify the Griddle Sensor
→ Disconnect appliance power before resistance testing
→ Inspect the sensor and its connections
→ Measure the Griddle Sensor resistance
→ Determine whether the sensor reads open
→ If the sensor reads open, replace the sensor
→ If the sensor is not open but F51 continues, inspect the associated wiring and connections
→ Use model-specific service information for additional diagnosis if necessary
The key diagnostic step is confirming whether the Griddle Sensor itself has an open resistance condition.
Can You Clear the F51 Code?
Disconnecting and restoring power may temporarily reset the electronic control.
However, a power reset cannot restore electrical continuity to an open Griddle Sensor.
If the sensor remains open, F51 may return.
A persistent F51 should therefore be diagnosed rather than repeatedly cleared through power cycling.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F51 repeatedly returns
- The griddle does not operate normally
- The Griddle Sensor requires resistance testing
- The sensor wiring requires inspection
- The sensor does not read open but F51 continues
- Internal access is required to reach the sensor circuit
A technician can isolate the Griddle Sensor from the rest of the circuit and determine whether the sensor itself is open or whether another part of the circuit is interrupting the signal.
Key Point
F51 indicates a Griddle Sensor Open Error.
The direct diagnostic procedure is:
Check Griddle Sensor → If the sensor reads open resistance → Replace sensor.
The source does not provide a specific normal resistance or voltage value for F51, so electrical specifications from other LG sensor codes should not be applied to this sensor.
F52 — Griddle Sensor Shorted Error
The F52 error code indicates a problem with the Griddle Sensor circuit in an LG range or oven.
LG identifies F52 as a Griddle Sensor Shorted Error and directs diagnosis toward the Griddle Sensor itself.
The published troubleshooting information is brief, so diagnosis should remain focused on the sensor and its circuit without applying specifications from unrelated LG temperature sensors.
What the F52 Error Code Means
F52 is identified as:
Griddle Sensor Shorted Error
The Griddle Sensor provides temperature-related information to the appliance’s electronic control system.
When the sensor circuit develops an abnormal electrical condition, the control may no longer be able to interpret the griddle temperature signal correctly and may display F52.
Common Causes
Because F52 is specifically associated with the Griddle Sensor circuit, areas requiring inspection may include:
- Griddle Sensor
- Sensor connector
- Sensor wiring
- Damaged wire insulation
- Shorted conductors
- Loose electrical connection
- Damaged terminals
- Sensor circuit connection
The error code alone should not be used to replace components without first evaluating the sensor circuit.
What You Can Check
If F52 appears, note the circumstances surrounding the error.
Useful observations include:
- Whether F52 appears when the griddle is activated
- Whether the griddle heats normally
- Whether the code appears immediately
- Whether F52 is intermittent or persistent
- Whether the appliance was recently serviced
- Whether the sensor wiring has been disturbed
- Whether there is visible damage near the sensor circuit
- The complete LG model number
These observations can provide useful context before electrical testing begins.
Check the Griddle Sensor
The direct F52 troubleshooting instruction is to:
Check Griddle Sensor.
The sensor should be electrically evaluated with the appliance safely disconnected from power.
Because the code concerns an abnormal sensor circuit, diagnosis should determine whether the Griddle Sensor itself is electrically abnormal or whether the problem exists elsewhere in the sensor circuit.
Check the Sensor Wiring and Connections
The sensor connections should also be inspected for obvious problems.
Look for:
- Loose connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Poor electrical contact
- Conductors contacting incorrectly
A wiring problem can affect the electrical characteristics seen by the electronic control even if the sensor itself is functional.
Understanding a Shorted Sensor Circuit
A shorted sensor circuit generally means the electrical path has developed an unintended low-resistance condition.
Possible areas to investigate include:
- Internally damaged sensor
- Damaged sensor wiring
- Conductors contacting each other
- Damaged insulation
- Connector or terminal problem
The sensor should be isolated and tested according to the appropriate model-specific diagnostic procedure to determine where the abnormal condition originates.
Important Note About the Published F52 Procedure
There is an inconsistency in the published F52 information.
The page identifies the code as:
Griddle Sensor Shorted Error
but its specified solution states:
If sensor reads open resistance then replace sensor.
Because these describe different electrical conditions, the safest diagnostic approach is not to assume an undocumented resistance threshold.
Instead, verify the Griddle Sensor and its circuit using the service information for the exact LG model.
Sensor vs. Wiring Diagnosis
The Griddle Sensor should be isolated from the rest of the circuit whenever possible during diagnosis.
If the sensor itself produces an abnormal electrical reading, the sensor becomes the primary area of investigation.
If the sensor tests according to the model-specific specification but F52 continues, diagnosis should move toward:
- Sensor connector
- Wiring harness
- Electrical terminals
- Complete sensor signal path
- Control-side connection
This helps prevent unnecessary sensor replacement when the actual problem is elsewhere in the circuit.
No Normal Resistance Specification Is Provided
The direct F52 page does not provide a normal numerical resistance value for the Griddle Sensor.
It also does not provide:
- A voltage specification
- A temperature/resistance table
- A specific short-circuit resistance threshold
Therefore, values from other LG temperature sensors should not be applied to F52.
Any precise electrical measurement should be compared with service documentation for the exact appliance model.
F51 vs. F52
F51 and F52 are closely related Griddle Sensor codes.
F51 — Griddle Sensor Open Error
F52 — Griddle Sensor Shorted Error
Conceptually, these represent two different types of abnormal sensor-circuit conditions:
F51 → Open circuit condition
F52 → Shorted circuit condition
However, the published F52 troubleshooting page contains the unusual instruction to replace the sensor if it reads open resistance.
Because of this inconsistency, model-specific service information should be consulted when precise electrical diagnosis is required.
Why the Griddle Sensor Matters
The Griddle Sensor provides temperature feedback used by the appliance’s electronic control system.
If the sensor circuit becomes electrically abnormal, reliable temperature information may no longer be available.
The control may therefore interrupt normal griddle operation and display an error rather than continue operating without reliable sensor feedback.
F52 Diagnostic Sequence
A practical diagnostic sequence is:
F52 displayed
→ Confirm the complete LG model number
→ Identify the Griddle Sensor circuit
→ Disconnect appliance power before resistance testing
→ Inspect the Griddle Sensor and connector
→ Inspect wiring for damage or shorted conductors
→ Electrically test the Griddle Sensor
→ Compare the result with model-specific service information
→ If the sensor is defective, replace the sensor
→ If the sensor tests correctly, continue through the wiring and connections
→ Perform further control-side diagnosis if necessary
This approach accounts for the limited and internally inconsistent information provided by the F52 source.
Can You Clear the F52 Code?
Disconnecting and restoring power may temporarily reset the electronic control and remove F52 from the display.
However, a reset cannot repair:
- Defective Griddle Sensor
- Shorted sensor circuit
- Damaged wiring
- Poor electrical connection
- Persistent sensor-circuit fault
If F52 returns, the Griddle Sensor circuit should be diagnosed rather than repeatedly resetting the appliance.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F52 repeatedly returns
- The griddle does not operate normally
- The Griddle Sensor requires resistance testing
- Internal sensor wiring requires inspection
- The sensor circuit must be isolated
- The sensor appears normal but F52 continues
A technician can isolate the sensor from the wiring and compare its electrical characteristics with the correct service specifications for the exact LG model.
Key Point
F52 is identified as a Griddle Sensor Shorted Error.
The direct source instructs technicians to:
Check the Griddle Sensor.
However, the same source states that the sensor should be replaced if it reads open resistance, creating an inconsistency between the error description and the published solution.
Because no numerical resistance specification is provided, use model-specific service information for precise electrical diagnosis rather than applying values from other LG sensor circuits.
F56 — Griddle Is Too Hot Error
The F56 error code indicates that the griddle temperature in an LG range has become excessively high during cooking.
The electronic control monitors griddle temperature through a thermistor. If the detected temperature remains above 650°F continuously for two minutes during cooking, the appliance may display F56.
What the F56 Error Code Means
F56 is identified as:
Griddle Is Too Hot Error
The defining condition is:
Griddle temperature exceeds 650°F continuously for 2 minutes during cooking.
This is an over-temperature fault rather than simply a general Griddle Sensor error.
The direct diagnostic information identifies two primary possible causes:
- Thermistor is out of range
- Griddle gas valve relay on the Main PCB is stuck ON
These possibilities represent two different diagnostic paths: incorrect temperature feedback or continued gas-valve activation.
Common Causes
Diagnosis should focus on the griddle temperature sensing and gas valve control systems, including:
- Griddle thermistor out of range
- Abnormal thermistor resistance
- Thermistor circuit problem
- Griddle gas valve relay stuck ON
- Main PCB relay problem
- Persistent heating when the control should reduce or stop heat
Unlike F51 and F52, F56 is triggered by an over-temperature condition.
What You Can Check
If F56 appears, stop using the griddle and note what happened immediately before the code appeared.
Useful observations include:
- Whether the griddle became unusually hot
- Whether heating continued when it should have stopped
- Whether F56 appeared during normal cooking
- Whether the code appeared after approximately two minutes of excessive heating
- Whether the griddle continued heating after the temperature setting was reduced
- Whether F56 returns during another cooking cycle
- The complete LG model number
Continued heating when the griddle should be cycling off can be particularly important when diagnosing F56.
Check the Griddle Thermistor
The direct F56 diagnostic procedure provides a specific thermistor resistance reference:
1.09 kΩ at 77°F.
At approximately:
77°F → Griddle Thermistor ≈ 1.09 kΩ
The thermistor should be allowed to cool near the specified temperature before comparing its measured resistance with this reference.
Because a thermistor changes resistance with temperature, a measurement taken while the griddle is still hot should not be expected to match the 77°F specification.
Why Thermistor Accuracy Matters
The electronic control relies on the Griddle Thermistor to determine temperature.
If the thermistor is out of range, the Main PCB may receive incorrect temperature information.
This can interfere with normal temperature regulation and may contribute to an F56 condition.
The thermistor should therefore be checked before assuming that the Main PCB has failed.
Check the Griddle Gas Valve Relay
The second condition specifically identified for F56 is:
Griddle gas valve relay on Main PCB is stuck ON.
The relay controls the electrical circuit associated with operation of the griddle gas valve.
If the relay remains electrically stuck in the ON state when the control is attempting to reduce or stop heating, the griddle may continue receiving heat.
This can result in an actual over-temperature condition.
Thermistor Problem vs. Stuck Relay
F56 has two fundamentally different diagnostic possibilities.
Thermistor out of range
The temperature-sensing system may provide abnormal information to the Main PCB.
Check:
Griddle Thermistor → 1.09 kΩ at 77°F
Griddle gas valve relay stuck ON
The heating system may continue operating when the control should stop or reduce heat.
Check:
Griddle Gas Valve Relay on Main PCB → possible stuck-ON condition
Identifying which condition is present is important before replacing components.
What If the Thermistor Tests Correctly?
If the Griddle Thermistor measures approximately 1.09 kΩ at 77°F, the published diagnostic path points toward checking the Griddle gas valve relay on the Main PCB for a possible stuck-ON condition.
Further diagnosis should determine whether heating continues when the control is no longer requesting it.
Because this involves the appliance’s gas-heating and electrical control systems, professional diagnosis is appropriate.
F56 vs. F51 and F52
F51, F52, and F56 all involve the griddle temperature system, but they represent different conditions.
F51 — Griddle Sensor Open Error
→ Sensor circuit is identified as open.
F52 — Griddle Sensor Shorted Error
→ Sensor circuit is identified as shorted.
F56 — Griddle Is Too Hot Error
→ Griddle temperature exceeds 650°F continuously for 2 minutes during cooking.
F56 also adds an important possible cause not present in the basic sensor codes:
Griddle gas valve relay on Main PCB stuck ON.
Why F56 Should Not Be Ignored
F56 represents an excessive-temperature condition.
If the griddle is continuing to heat when it should stop, repeatedly resetting the appliance without diagnosing the cause can allow the overheating condition to occur again.
Stop using the griddle if:
- Heating continues unexpectedly
- Temperature becomes excessively high
- F56 repeatedly returns
- The griddle does not respond correctly to temperature controls
The cause should be diagnosed before normal griddle operation resumes.
F56 Diagnostic Sequence
A practical diagnostic sequence is:
F56 displayed
→ Stop using the griddle and allow it to cool
→ Confirm the complete LG model number
→ Determine whether the griddle was actually overheating
→ Inspect the griddle temperature-sensing system
→ Measure the thermistor near the specified temperature
→ Compare with 1.09 kΩ at 77°F
→ If the thermistor is out of range, investigate the thermistor
→ If the thermistor tests correctly, check the Griddle gas valve relay on the Main PCB
→ Determine whether the relay is stuck ON
→ Continue with model-specific diagnosis as necessary
The goal is to distinguish between incorrect temperature feedback and continued heating caused by the gas valve control circuit.
Can You Clear the F56 Code?
Disconnecting and restoring power may temporarily clear F56 from the display.
However, resetting the appliance cannot repair:
- Out-of-range Griddle Thermistor
- Stuck gas valve relay
- Main PCB relay fault
- Persistent griddle overheating condition
If F56 returns, the griddle should not simply be reset and reused without determining why it is overheating.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F56 repeatedly returns
- The griddle becomes excessively hot
- Heating continues when it should stop
- The thermistor requires resistance testing
- The gas valve relay requires diagnosis
- A Main PCB relay problem is suspected
Because F56 can involve both gas control and electrical control circuitry, internal diagnosis should be performed by someone qualified to safely service the appliance.
Key Point
F56 indicates that the Griddle Is Too Hot.
The defining condition is:
Griddle temperature over 650°F continuously for 2 minutes during cooking.
The direct diagnostic specifications are:
Griddle Thermistor: 1.09 kΩ at 77°F
Alternative cause: Griddle gas valve relay on Main PCB stuck ON
Diagnostic direction: Check the thermistor and check the relay for a possible stuck-ON condition.
F56 should be treated as an over-temperature condition, not simply as another generic Griddle Sensor error.
F59 — Griddle Not Heating Error
The F59 error code indicates that the griddle in an LG range is not heating as expected after cooking begins.
The electronic control monitors the Griddle Thermistor to determine whether the temperature is increasing normally. If the expected temperature rise does not occur within the specified time, the appliance may display F59.
What the F59 Error Code Means
LG identifies F59 as:
Griddle Not Heating Error
The error can be triggered by either of two temperature conditions:
- The griddle temperature does not increase by more than 30°F compared with the starting temperature within 5 minutes after cooking begins
- The griddle temperature remains below 100°F for 5 minutes after cooking begins
These conditions indicate that the griddle is not producing or detecting the expected temperature increase.
Common Causes
The F59 diagnostic procedure focuses on the griddle heating and temperature-sensing systems.
Possible areas requiring diagnosis include:
- Gas valve electrical supply
- Griddle gas valve operation
- Gas valve control circuit
- Relay
- Damaged relay
- Griddle Thermistor
- Abnormal thermistor resistance
- Associated wiring and connections
The goal is to determine whether the griddle is actually failing to heat or whether the temperature-sensing system is providing incorrect information.
What You Can Check
If F59 appears, note what happens when griddle cooking is started.
Useful observations include:
- Whether the griddle produces any heat
- Whether it heats very slowly
- Whether the temperature appears unchanged
- Whether F59 appears approximately five minutes after cooking starts
- Whether the griddle begins heating and then stops
- Whether the code returns every time the griddle is used
- Whether other cooking functions operate normally
- The complete LG model number
These observations can help distinguish a complete no-heat condition from inadequate heating or an inaccurate temperature signal.
Check the Griddle Temperature Rise
F59 uses the griddle’s temperature behavior during the first five minutes of cooking as part of its detection logic.
One trigger occurs when the temperature fails to rise by more than:
30°F above the starting temperature within 5 minutes.
For example, the important diagnostic factor is not simply the final temperature but whether the griddle produces the expected increase from its starting temperature.
This allows the control to recognize that a heating cycle has started without producing sufficient heat.
Check for a Low-Temperature Condition
The second F59 trigger occurs when:
Griddle temperature remains below 100°F for 5 minutes after cooking starts.
This represents a more direct no-heat or extremely low-heat condition.
Together, the two detection conditions allow the control to identify inadequate griddle heating based on both temperature rise and absolute temperature.
Check Voltage to the Gas Valve
The direct F59 diagnostic procedure instructs technicians to:
Check voltage to the gas valve.
If the gas valve is not receiving the required electrical command, the griddle may fail to produce heat even though a cooking cycle has been selected.
Diagnosis should therefore determine whether the gas valve is being electrically activated when griddle heating is requested.
The F59 source does not specify a numerical voltage value, so the correct voltage specification should be obtained from service information for the exact LG model.
Check the Relay
The direct troubleshooting procedure also specifies:
Check relay for possible damage.
The relay is part of the electrical control path responsible for activating the griddle heating system.
If the relay is damaged or fails to switch correctly, the gas valve may not receive the electrical command necessary for normal heating.
The relay should therefore be evaluated when the griddle does not heat and F59 is displayed.
Check the Griddle Thermistor
F59 also provides a specific resistance reference for the Griddle Thermistor:
1.09 kΩ at 77°F.
The thermistor should be tested near the specified temperature when comparing its resistance with this reference.
Because thermistor resistance changes with temperature, a measurement taken while the griddle is still hot should not be expected to match the 77°F specification.
Why the Thermistor Matters
The Main PCB relies on temperature feedback from the Griddle Thermistor to determine whether the griddle is heating.
If the thermistor provides an incorrect temperature signal, the control may interpret the griddle as failing to heat even if some heating is occurring.
This creates two fundamentally different possibilities:
Actual no-heat condition
→ The griddle is not producing sufficient heat.
Temperature-sensing problem
→ The griddle may be heating, but the control is receiving incorrect temperature information.
Checking the thermistor helps distinguish between these conditions.
Heating System vs. Temperature Sensor Diagnosis
A useful F59 diagnostic approach is to separate the heating side from the sensing side.
Heating side:
Gas valve → voltage supply → relay/control circuit
Temperature-sensing side:
Griddle Thermistor → temperature feedback → electronic control
If the thermistor measures approximately 1.09 kΩ at 77°F, attention can move toward whether the gas valve is receiving the appropriate electrical command and whether the relay is functioning correctly.
If the thermistor reading is abnormal, the temperature-sensing circuit requires further diagnosis.
No Gas Valve Voltage Specification Is Provided
The F59 source says to check voltage to the gas valve but does not provide a specific voltage value.
Therefore, a universal voltage specification should not be added to the diagnostic procedure.
Use the service documentation for the exact LG model when determining the expected gas-valve voltage.
This avoids applying specifications from a different range or control configuration.
F59 vs. F56
F56 and F59 describe opposite griddle temperature conditions.
F56 — Griddle Is Too Hot Error
→ Griddle temperature exceeds 650°F continuously for 2 minutes during cooking
F59 — Griddle Not Heating Error
→ Temperature fails to rise more than 30°F from the starting temperature within 5 minutes, or remains below 100°F for 5 minutes
Both codes use a Griddle Thermistor reference of:
1.09 kΩ at 77°F
But their diagnostic directions differ:
F56 → Excessive heating / possible stuck-ON gas valve relay
F59 → Insufficient heating / check gas valve voltage and relay for possible damage
This makes F56 and F59 useful opposite-condition diagnostic codes.
F51, F52, F56, and F59
These four codes cover several different types of griddle-related faults:
F51 — Griddle Sensor Open Error
→ Open sensor condition
F52 — Griddle Sensor Shorted Error
→ Shorted sensor condition
F56 — Griddle Is Too Hot Error
→ Excessive griddle temperature
F59 — Griddle Not Heating Error
→ Insufficient temperature rise after cooking begins
Together, they help distinguish between sensor-circuit faults and actual temperature-control problems.
F59 Diagnostic Sequence
A practical diagnostic sequence is:
F59 displayed
→ Confirm the complete LG model number
→ Determine whether the griddle is producing heat
→ Note whether the temperature rises during the first 5 minutes
→ Check the Griddle Thermistor
→ Compare thermistor resistance with 1.09 kΩ at 77°F
→ Check voltage to the gas valve
→ Check the relay for possible damage
→ Inspect associated wiring and connections
→ Continue with model-specific diagnosis if necessary
This sequence helps separate a temperature-sensing problem from a failure of the griddle heating system.
Can You Clear the F59 Code?
Disconnecting and restoring power may temporarily clear F59.
However, a reset cannot repair:
- Griddle that is not heating
- Gas valve control problem
- Damaged relay
- Abnormal Griddle Thermistor
- Wiring or connection problem
If F59 returns when griddle cooking is started, the heating and temperature-sensing systems should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F59 repeatedly returns
- The griddle produces little or no heat
- The Griddle Thermistor requires resistance testing
- Gas valve voltage needs to be measured
- The relay requires diagnosis
- Internal wiring requires inspection
- The thermistor tests normally but the griddle still does not heat
Because F59 can involve both the gas system and energized electrical control circuitry, internal testing should be performed using appropriate service and electrical safety procedures.
Key Point
F59 indicates a Griddle Not Heating Error.
The code can be triggered when:
Temperature rise ≤ approximately 30°F from the starting temperature during the first 5 minutes of cooking
or
Griddle temperature remains below 100°F for 5 minutes after cooking begins.
The direct diagnostic procedure specifies:
Check voltage to gas valve
Check relay for possible damage
Check Griddle Thermistor → 1.09 kΩ at 77°F.
F59 should therefore be diagnosed by evaluating both the griddle heating system and its temperature-feedback circuit.
F6 — Upper Oven Too Hot
The F6 error code indicates that the upper oven in an LG range has reached an abnormally high temperature during normal operation.
The control monitors oven temperature through the Upper Oven Sensor. If the detected temperature remains above 650°F continuously for more than two minutes, the appliance may display F6.
This detection condition does not apply during Self Clean, when the oven is designed to operate at much higher temperatures.
What the F6 Error Code Means
F6 is identified as:
Upper Oven Too Hot
The defining condition is:
Upper oven temperature is over 650°F continuously for more than 2 minutes, except during Self Clean.
This makes F6 an over-temperature fault, rather than simply a general temperature-sensor error.
The diagnostic procedure begins by allowing the oven to cool and checking the Upper Oven Sensor resistance.
Common Causes
An F6 condition can involve the upper oven temperature-sensing or temperature-control system.
Areas requiring diagnosis may include:
- Upper Oven Sensor
- Abnormal sensor resistance
- Sensor wiring
- Sensor connector
- Temperature feedback circuit
- Heating system that continues operating unexpectedly
- Electronic control system
The error code alone should not be used to determine which component has failed. The actual oven temperature and sensor circuit should first be evaluated.
What You Can Check
If F6 appears, stop using the upper oven and allow it to cool.
Note:
- Whether the oven became unusually hot
- Whether heating continued after reaching the set temperature
- Whether the displayed temperature appeared abnormal
- Whether F6 occurred during Bake, Broil, or another cooking mode
- Whether F6 appeared during Self Clean
- Whether the error returns after the oven cools
- Whether temperature regulation has recently become inconsistent
- The complete LG model number
The operating mode matters because the 650°F / two-minute condition specifically excludes Self Clean.
Allow the Oven to Cool Before Testing
The direct F6 troubleshooting procedure instructs technicians to measure the Oven Sensor resistance after the oven has cooled down.
This is important because an oven temperature sensor changes resistance with temperature.
Testing a hot sensor and comparing it with a room-temperature specification can produce a misleading result.
Allow the oven to return approximately to room temperature before evaluating the published resistance range.
Check the Upper Oven Sensor Resistance
The F6 diagnostic information provides the following reference range:
Approximately 1.06 kΩ at 65°F to 1.12 kΩ at 85°F.
This provides a useful room-temperature reference for evaluating the Upper Oven Sensor.
After the oven has cooled:
65°F → approximately 1.06 kΩ
85°F → approximately 1.12 kΩ
A reading significantly outside the expected range can indicate a problem requiring further diagnosis.
Why the Oven Sensor Matters
The Upper Oven Sensor provides temperature feedback to the electronic control.
The control uses this information to determine:
- Current oven temperature
- When heating should continue
- When heating should stop or cycle
- Whether temperature is within the expected operating range
If the sensor provides incorrect temperature information, the control may interpret oven conditions incorrectly.
This is why checking the sensor is an important first diagnostic step for F6.
Check the Sensor Wiring and Connections
If the sensor resistance is reasonable but F6 continues, inspect the associated sensor circuit.
Look for:
- Loose connector
- Damaged sensor wiring
- Broken conductor
- Poor terminal contact
- Heat-damaged connector
- Backed-out terminal
- Intermittent connection
The control depends on the complete electrical path between the Upper Oven Sensor and the control system.
A sensor can test normally by itself while a wiring or connection problem still interferes with the temperature signal.
Actual Overheating vs. Incorrect Temperature Reading
An important part of F6 diagnosis is determining whether the upper oven is actually overheating or whether the control is receiving incorrect temperature information.
Sensor / feedback problem
The actual oven temperature may not be excessively high, but abnormal sensor information can cause the control to detect an over-temperature condition.
Actual overheating
The upper oven may continue heating beyond its normal operating temperature.
These conditions require different diagnostic paths, so the sensor and actual heating behavior should both be considered.
What If the Sensor Tests Normally?
If the Upper Oven Sensor measures within the expected range after cooling but F6 continues, further diagnosis is required.
The next areas may include:
- Sensor wiring
- Sensor connectors
- Temperature feedback circuit
- Heating control
- Electronic control system
- Model-specific oven circuitry
A normal room-temperature sensor reading does not by itself prove that every part of the temperature-control system is operating correctly.
F6 vs. F16
F6 and F16 are closely related over-temperature codes but apply to different oven sections.
F6 — Upper Oven Too Hot
→ Upper oven exceeds 650°F continuously for more than 2 minutes
→ Self Clean excluded
F16 — Lower Oven Too Hot
→ Lower oven exceeds 650°F continuously for more than 2 minutes
→ Self Clean excluded
Both use the same published room-temperature sensor reference:
Approximately 1.06 kΩ at 65°F – 1.12 kΩ at 85°F
The important distinction is oven location:
F6 → Upper Oven
F16 → Lower Oven
F6 vs. F1
F6 should also be distinguished from the Upper Oven Thermistor-related F1 condition.
F1 — Upper Oven Thermistor Error
→ The control is not receiving the expected Upper Oven Sensor signal.
F6 — Upper Oven Too Hot
→ The control detects an upper oven temperature above 650°F for more than two continuous minutes, outside Self Clean.
Therefore, F1 is primarily a sensor signal fault, while F6 is an over-temperature detection fault.
F6 Diagnostic Sequence
A practical diagnostic sequence is:
F6 displayed
→ Stop using the upper oven
→ Confirm the error occurred outside Self Clean
→ Allow the oven to cool
→ Confirm the complete LG model number
→ Check the Upper Oven Sensor resistance
→ Compare with approximately 1.06 kΩ at 65°F – 1.12 kΩ at 85°F
→ Inspect sensor wiring and connections
→ Determine whether the oven is actually overheating
→ If the sensor circuit appears normal, continue with model-specific heating/control diagnosis
The key is to distinguish an abnormal temperature-sensor signal from an actual uncontrolled heating condition.
Can You Clear the F6 Code?
Disconnecting and restoring power may temporarily clear F6.
However, a reset cannot repair:
- Abnormal Upper Oven Sensor
- Damaged sensor wiring
- Poor electrical connection
- Persistent temperature-control problem
- Actual uncontrolled overheating
If F6 returns, particularly if the upper oven becomes excessively hot, the appliance should be diagnosed before continued use.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F6 repeatedly returns
- The upper oven becomes excessively hot
- Heating continues unexpectedly
- The oven does not regulate temperature correctly
- The Upper Oven Sensor requires resistance testing
- The sensor tests normally but F6 continues
- Internal wiring or electronic controls require diagnosis
If the oven is clearly overheating, discontinue use until the cause has been identified.
Key Point
F6 indicates an Upper Oven Too Hot condition.
The defining condition is:
Upper oven temperature above 650°F continuously for more than 2 minutes, except during Self Clean.
After the oven cools, the published sensor reference is:
Approximately 1.06 kΩ at 65°F – 1.12 kΩ at 85°F.
Diagnosis should determine whether F6 is being caused by an abnormal Upper Oven Sensor/temperature-feedback circuit or by an actual upper-oven overheating condition.
F62 — Sous Vide Temperature Sensor Error
The F62 error code indicates a problem with the Sous Vide Temperature Sensor system in an LG range or oven.
The sous vide system relies on a thermistor to monitor temperature accurately. If the thermistor reading falls outside the expected range, the electronic control may detect the abnormal condition and display F62.
What the F62 Error Code Means
LG identifies F62 as:
Sous Vide Temperature Sensor Error
The direct diagnostic information identifies the cause as:
Thermistor out of range
The published troubleshooting procedure provides two specific electrical checks:
- Thermistor resistance: 98 kΩ at 77°F
- Heater supply: 120 VAC
This means diagnosis should evaluate both the temperature-sensing circuit and whether the sous vide heater is receiving the expected electrical supply.
Common Causes
Possible areas requiring diagnosis include:
- Sous Vide Thermistor
- Thermistor resistance out of range
- Thermistor connector
- Sensor wiring
- Poor electrical connection
- Sous vide heater circuit
- Missing 120 VAC supply to the heater
- Associated control circuitry
Because F62 is specifically identified as a temperature sensor error, the thermistor is a primary diagnostic point.
What You Can Check
If F62 appears, note how the sous vide function behaves.
Useful observations include:
- Whether the sous vide function begins heating
- Whether it reaches the selected temperature
- Whether heating stops unexpectedly
- Whether F62 appears immediately or after heating begins
- Whether temperature readings appear abnormal
- Whether F62 returns after restarting the appliance
- Whether the appliance was recently serviced
- The complete LG model number
These observations can help distinguish a temperature-sensing problem from a heating-system problem.
Check the Sous Vide Thermistor
The direct F62 diagnostic procedure specifies:
Thermistor resistance: 98 kΩ at 77°F.
This is the published reference point for evaluating the Sous Vide Thermistor.
At approximately:
77°F → 98 kΩ
Because thermistor resistance changes with temperature, the sensor should be near the specified temperature before comparing its resistance with this value.
Resistance testing should be performed with the appliance disconnected from electrical power.
Why the 77°F Reference Matters
A thermistor changes electrical resistance as its temperature changes.
Therefore, 98 kΩ is not a universal resistance value at every temperature. It is specifically the published reference at 77°F.
A sensor tested while substantially warmer or colder should not necessarily measure exactly 98 kΩ.
For precise testing at other temperatures, use the temperature/resistance specifications provided for the exact LG model.
Check the Thermistor Wiring and Connections
If the thermistor requires further diagnosis, inspect its electrical path for:
- Loose connector
- Connector not fully seated
- Damaged wiring
- Broken conductor
- Bent terminal
- Backed-out terminal
- Heat-damaged connection
- Poor electrical contact
An abnormal signal reaching the electronic control can result from either the thermistor itself or an interruption in its circuit.
Check for 120 VAC to the Heater
The second direct F62 diagnostic check is:
Check for 120 VAC to the heater.
This determines whether the sous vide heating system is receiving its specified electrical supply.
A simplified diagnostic path is:
Temperature sensing → Sous Vide Thermistor → 98 kΩ @ 77°F
Heating → Sous Vide Heater → 120 VAC
Both sides are relevant when diagnosing abnormal sous vide temperature operation.
Thermistor Problem vs. Heating Problem
F62 diagnosis should distinguish between incorrect temperature feedback and a heater that is not operating as expected.
Thermistor side
If the thermistor is out of range, the electronic control may receive incorrect temperature information.
Published reference:
98 kΩ @ 77°F
Heater side
If the heater does not receive its expected supply, normal sous vide heating cannot occur.
Published reference:
120 VAC to heater
These two measurements help determine which side of the system requires further investigation.
What If the Thermistor Tests Correctly?
If the Sous Vide Thermistor measures approximately 98 kΩ at 77°F, but F62 continues, further diagnosis may include:
- Thermistor wiring
- Sensor connectors
- Heater supply
- Heater circuit
- Control-side connections
- Model-specific electronic control system
The direct source specifically includes the 120 VAC heater check, so the heating circuit should not be ignored simply because the thermistor appears normal.
What If 120 VAC Is Missing?
If the expected 120 VAC is not present at the heater when the system should be heating, further diagnosis is required.
The problem may be somewhere in the heater’s electrical supply or control path.
Model-specific service documentation should be used to trace the circuit rather than assuming a particular control component has failed.
F62 by itself does not prove that the Main PCB or heater is defective.
F62 Uses a Different Thermistor Specification
The 98 kΩ @ 77°F value is specific to the Sous Vide Thermistor diagnostic information for F62.
It should not be confused with values used for other LG sensors, such as:
- Griddle Thermistor — 1.09 kΩ @ 77°F
- Induction Burner Temperature Sensor — 57 kΩ @ 77°F
- Other oven temperature sensors with their own resistance ranges
Always use the specification associated with the correct sensor and error code.
F62 Diagnostic Sequence
A practical diagnostic sequence is:
F62 displayed
→ Confirm the complete LG model number
→ Identify the Sous Vide Temperature Sensor circuit
→ Inspect thermistor wiring and connections
→ Measure thermistor resistance near 77°F
→ Compare with 98 kΩ @ 77°F
→ Determine whether the thermistor is out of range
→ Check for 120 VAC to the sous vide heater when appropriate
→ If either measurement is abnormal, diagnose that circuit
→ If both measurements are correct, continue with model-specific diagnosis
This approach evaluates both temperature feedback and heater operation without prematurely identifying a failed component.
Can You Clear the F62 Code?
Disconnecting and restoring power may temporarily clear F62.
However, resetting the appliance cannot repair:
- Out-of-range thermistor
- Damaged sensor wiring
- Poor electrical connection
- Missing heater voltage
- Persistent sous vide temperature-control problem
If F62 returns, the temperature sensor and heating circuits should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F62 repeatedly returns
- The sous vide function does not heat correctly
- Temperature regulation is inaccurate
- Thermistor resistance requires testing
- The 120 VAC heater supply requires measurement
- Internal wiring or control circuitry requires diagnosis
Testing for 120 VAC requires live electrical measurements and should only be performed using appropriate electrical safety procedures.
Key Point
F62 indicates a Sous Vide Temperature Sensor Error.
The direct source identifies:
Cause: Thermistor out of range
Thermistor reference: 98 kΩ at 77°F
Heater check: 120 VAC to heater.
Diagnosis should therefore evaluate both the Sous Vide Thermistor and the heater electrical supply, rather than assuming the sensor or control board has failed based on the error code alone.
F69 — Sous Vide Not Heating Error
The F69 error code indicates that the Sous Vide system in an LG range or oven is not heating properly.
The Sous Vide system relies on several components working together: a thermostat, heater, temperature-sensing thermistor, electrical supply, and associated control circuitry. If the heating system cannot produce the expected temperature increase, the appliance may display F69.
What the F69 Error Code Means
LG identifies F69 as:
Sous Vide Not Heating Error
The direct diagnostic information identifies four possible conditions:
- Thermostat is open
- Heater is open
- Required voltage is missing
- Thermistor is out of range
This means F69 does not automatically identify one failed component. The complete Sous Vide heating and temperature-sensing system should be evaluated.
Common Causes
Possible areas requiring diagnosis include:
- Open Sous Vide thermostat
- Open Sous Vide heater
- Abnormal heater resistance
- Missing voltage to the heater
- Sous Vide Thermistor out of range
- Thermistor wiring or connections
- Heater wiring or connections
- Associated electrical control circuit
The direct diagnostic procedure provides specific checks for the thermostat, heater, thermistor, and heater voltage.
What You Can Check
If F69 appears, note how the Sous Vide function behaves.
Useful observations include:
- Whether the Sous Vide function produces any heat
- Whether heating begins and then stops
- Whether the temperature rises slowly
- Whether F69 appears immediately or after heating begins
- Whether the displayed temperature appears reasonable
- Whether the code returns each time Sous Vide is selected
- Whether the appliance was recently serviced
- The complete LG model number
These observations can help determine whether the problem is a complete no-heat condition or an abnormal temperature-sensing condition.
Check the Thermostat Continuity
The direct F69 troubleshooting procedure specifically instructs technicians to:
Check thermostat continuity.
An open thermostat can interrupt the electrical path required for Sous Vide heating.
With the appliance safely disconnected from electrical power, the thermostat circuit can be checked for continuity according to the service procedure for the specific model.
If the thermostat is open when it should provide continuity, the Sous Vide heater may be unable to operate.
Check the Sous Vide Heater Resistance
LG provides a specific resistance value for the heater:
Sous Vide Heater: 18 Ω
Resistance testing can help determine whether the heater itself has an open or otherwise abnormal electrical condition.
A simplified check is:
Heater resistance → approximately 18 Ω
An open reading would be consistent with the source’s listed possibility of an open heater.
Resistance measurements should be performed with power disconnected.
Check the Sous Vide Thermistor
The direct F69 diagnostic information also provides a specific thermistor reference:
Sous Vide Thermistor: 98 kΩ at 77°F
Because thermistor resistance changes with temperature, this value should be compared when the sensor is approximately at the specified temperature.
At approximately:
77°F → 98 kΩ
A significantly abnormal measurement can indicate that the thermistor is out of range.
Why Thermistor Temperature Matters
The 98 kΩ specification applies specifically at 77°F.
A thermistor changes resistance as temperature changes, so a sensor measured at a substantially different temperature should not necessarily read exactly 98 kΩ.
If precise resistance values at other temperatures are required, use service information for the exact LG model.
Check for 120 VAC to the Heater
The fourth specific F69 diagnostic check is:
Check for 120 VAC to the heater.
This measurement helps distinguish between a heater that cannot operate electrically and a heater that simply is not receiving its required supply.
A simplified diagnostic distinction is:
120 VAC present + heater does not heat correctly
→ Investigate the heater and its immediate circuit.
120 VAC missing when heating should occur
→ Investigate the electrical supply/control path to the heater.
Testing for 120 VAC requires live electrical measurements and appropriate safety procedures.
Heater Resistance vs. Heater Voltage
F69 provides two different checks for the heating element:
Heater resistance: 18 Ω
Heater supply: 120 VAC
These measurements answer different diagnostic questions.
The 18 Ω resistance check evaluates the electrical condition of the heater itself.
The 120 VAC check determines whether the heating circuit is delivering the required operating voltage to the heater.
A heater can therefore fail to produce heat either because the heater circuit itself is open or because the required voltage never reaches it.
Temperature Sensor vs. Heating System Diagnosis
F69 diagnosis can be divided into two major areas.
Temperature feedback system:
Sous Vide Thermistor
→ 98 kΩ @ 77°F
Heating system:
Thermostat
→ Check continuity
Heater
→ 18 Ω
Heater supply
→ 120 VAC
This helps distinguish a temperature-feedback problem from an actual failure of the heating circuit.
What If the Heater Measures 18 Ω?
If the heater measures approximately 18 Ω, that suggests the heater is not electrically open under the conditions of the test.
Diagnosis should then continue with:
- Thermostat continuity
- 120 VAC heater supply
- Thermistor resistance
- Wiring and connections
- Model-specific control circuitry
A normal heater resistance measurement alone does not confirm that the complete Sous Vide heating system is functioning correctly.
What If 120 VAC Is Missing?
If the heater does not receive 120 VAC when it should be energized, further diagnosis should focus on the heater’s electrical supply and control path.
Inspect the applicable:
- Wiring
- Connections
- Thermostat circuit
- Control-side circuit
The direct F69 information does not identify a particular PCB or relay as the automatic cause of missing voltage, so a control board should not be condemned based on F69 alone.
F69 vs. F62
F62 and F69 both involve the Sous Vide system, but they describe different fault conditions.
F62 — Sous Vide Temperature Sensor Error
→ Thermistor out of range
→ 98 kΩ @ 77°F
→ Check 120 VAC to heater
F69 — Sous Vide Not Heating Error
→ Thermostat open, heater open, missing voltage, or thermistor out of range
→ Check thermostat continuity
→ Heater: 18 Ω
→ Thermistor: 98 kΩ @ 77°F
→ Heater supply: 120 VAC
F62 is primarily identified as a temperature sensor fault, while F69 provides a broader diagnostic path for a Sous Vide no-heat condition.
F69 Diagnostic Sequence
A practical diagnostic sequence is:
F69 displayed
→ Confirm the complete LG model number
→ Determine whether the Sous Vide system produces any heat
→ Disconnect power before resistance/continuity testing
→ Check thermostat continuity
→ Measure heater resistance
→ Compare with 18 Ω
→ Measure Sous Vide Thermistor resistance near 77°F
→ Compare with 98 kΩ @ 77°F
→ When appropriate, check for 120 VAC to the heater
→ Inspect associated wiring and connections
→ Continue with model-specific control diagnosis if necessary
This sequence evaluates each of the specific areas identified by the F69 diagnostic information.
Can You Clear the F69 Code?
Disconnecting and restoring power may temporarily clear F69.
However, resetting the appliance cannot repair:
- Open thermostat
- Open heater
- Missing heater voltage
- Out-of-range thermistor
- Damaged wiring or connections
If F69 returns when the Sous Vide function is used, the heating and temperature-sensing circuits should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F69 repeatedly returns
- The Sous Vide system does not heat
- Thermostat continuity requires testing
- Heater resistance requires testing
- Thermistor resistance requires testing
- The 120 VAC heater supply requires measurement
- Internal wiring or control circuitry requires diagnosis
Live voltage testing should only be performed using appropriate electrical safety procedures.
Key Point
F69 indicates a Sous Vide Not Heating Error.
The direct diagnostic information identifies four possible conditions:
Thermostat open
Heater open
Missing voltage
Thermistor out of range
The published checks are:
Thermostat → check continuity
Heater → 18 Ω
Thermistor → 98 kΩ @ 77°F
Heater supply → 120 VAC.
These checks help distinguish between a temperature-sensing problem, heater failure, thermostat problem, and missing heater power.
F7 — Upper Convection Fan Error
The F7 error code usually indicates a problem with the Upper Convection Fan system in an LG range or oven.
The electronic control monitors convection fan operation. If operation of the Upper Convection Fan cannot be detected for more than one minute, the appliance may display F7.
However, several older LG electric range models use F7 differently, making the complete model number especially important when diagnosing this code.
What the F7 Error Code Means
For most LG ranges and ovens:
F7 = Upper Convection Fan Error
The defining condition is:
Convection fan operation cannot be detected for over 1 minute.
The direct troubleshooting procedure instructs technicians to check the harness connections at:
- Convection Fan
- Main PCB
This means F7 does not automatically confirm that the fan motor itself has failed.
Important Model Exception
Several older LG electric ranges assign a different meaning to F7.
The affected models listed by the source are:
- LRE3012
- LRE30451
- LRE30453
- LRE30757
For these models:
F7 = Oven Not Heating
The source instructs technicians to use the F9 error-code troubleshooting procedure for this condition.
Therefore:
Most models → Upper Convection Fan Error
LRE3012 / LRE30451 / LRE30453 / LRE30757 → Oven Not Heating
Always verify the complete model number before diagnosing F7.
Common Causes
For models where F7 means Upper Convection Fan Error, diagnosis should focus on the convection fan circuit.
Possible areas requiring inspection include:
- Upper Convection Fan
- Fan electrical connector
- Fan wiring harness
- Loose harness connection
- Damaged wiring
- Poor terminal contact
- Main PCB connection
- Fan operation not being detected by the control
The direct source specifically identifies the Convection Fan and Main PCB harness connections as the initial diagnostic points.
What You Can Check
If F7 appears, note how the upper oven behaves.
Useful observations include:
- Whether the convection fan starts
- Whether the fan can be heard operating
- Whether the fan starts and then stops
- Whether unusual fan noises are present
- Whether F7 appears shortly after convection operation begins
- Whether the fan appears mechanically restricted
- Whether the appliance was recently serviced
- Whether the error is intermittent or persistent
- The complete LG model number
Checking the model number should come first because the four older models use F7 for a completely different fault.
Check the Upper Convection Fan
For most models, F7 indicates that convection fan operation is not being detected correctly.
The fan should be inspected for obvious problems such as:
- Fan not rotating
- Fan blade obstruction
- Mechanical binding
- Damaged fan blade
- Fan starting and stopping unexpectedly
- Unusual noise during operation
A fan that cannot rotate normally may prevent the system from detecting expected convection operation.
Check the Convection Fan Harness
The direct F7 procedure specifically instructs technicians to check the:
Harness at the Convection Fan.
With the appliance safely disconnected from power, inspect the connection for:
- Loose connector
- Connector not fully seated
- Broken wire
- Damaged insulation
- Bent terminal
- Backed-out terminal
- Heat damage
- Poor electrical contact
A connection problem can prevent normal fan operation or interfere with the control’s ability to detect it.
Check the Main PCB Connection
The other specific inspection point identified by the source is the:
Main PCB harness connection.
The electrical path should therefore be considered as a complete circuit:
Main PCB → Wiring Harness → Upper Convection Fan
A poor connection anywhere along this path can contribute to the F7 condition.
Fan Motor vs. Wiring Diagnosis
F7 should not automatically lead to replacement of the Upper Convection Fan.
The direct troubleshooting procedure emphasizes the harness at both the fan and Main PCB.
A practical distinction is:
Fan does not operate
→ Inspect the fan, harness, connectors, and associated electrical circuit.
Fan appears to operate but F7 still occurs
→ Further diagnosis may be required to determine why fan operation is not being correctly detected.
The exact model-specific service documentation should be used for electrical testing beyond the published basic procedure.
No Resistance or Voltage Specification Is Provided
The direct F7 page does not provide a fan resistance or voltage specification.
Therefore, electrical values from other LG fan codes should not be applied to F7.
For example, specifications published for Box Fan or induction cooling fan errors should not automatically be used for the Upper Convection Fan.
If electrical measurements are required, use the service information for the exact LG model.
F7 vs. F17
F7 and F17 are closely related convection fan codes but apply to different oven sections.
F7 — Upper Convection Fan Error
→ Convection fan operation cannot be detected for over 1 minute.
F17 — Lower Convection Fan Error
→ Lower convection fan operation cannot be detected for over 1 minute.
Both direct diagnostic procedures point toward checking the harness at the Convection Fan and Main PCB.
The key distinction is:
F7 → Upper Oven
F17 → Lower Oven
Why the One-Minute Detection Period Matters
F7 is not simply generated because the fan is momentarily stationary.
The published trigger specifies that convection fan operation cannot be detected for:
Over 1 minute.
This timing should be preserved when describing the code because it explains what condition the control is monitoring.
F7 Diagnostic Sequence
A practical diagnostic sequence is:
F7 displayed
→ Confirm the complete LG model number
→ Determine whether the appliance is LRE3012, LRE30451, LRE30453, or LRE30757
→ If one of those models, treat F7 as an Oven Not Heating error and use the applicable F9 diagnostic information
→ For other models, identify the Upper Convection Fan
→ Check whether the fan operates
→ Inspect for mechanical obstruction
→ Check the harness at the Convection Fan
→ Check the harness connection at the Main PCB
→ Inspect associated wiring and terminals
→ Continue with model-specific electrical diagnosis if necessary
This sequence prevents the older-model F7 definition from being confused with the convection fan fault used by most models.
Can You Clear the F7 Code?
Disconnecting and restoring power may temporarily clear F7.
However, a reset cannot repair:
- Non-operating convection fan
- Mechanical fan problem
- Damaged wiring
- Loose harness connection
- Persistent fan-control or detection problem
- Oven heating problem on the affected older models
If F7 returns, diagnose the system corresponding to the exact model.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F7 repeatedly returns
- The Upper Convection Fan does not operate
- The fan makes abnormal noises
- Wiring or harness connections require internal inspection
- The fan operates but F7 continues
- The appliance is one of the older models where F7 means Oven Not Heating
- Further electrical diagnosis is required
The model number should always be confirmed before replacing parts.
Key Point
For most LG ranges and ovens:
F7 = Upper Convection Fan Error
The control cannot detect convection fan operation for more than one minute, and the direct troubleshooting procedure is to check the harness at the Convection Fan and Main PCB.
However:
LRE3012, LRE30451, LRE30453, LRE30757 → F7 = Oven Not Heating
For those older models, LG Error Codes directs diagnosis to the F9 troubleshooting procedure.
F8 — Upper Oven Meat Probe Error
The F8 error code indicates a problem with the Upper Oven Meat Probe Sensor circuit in an LG range or oven.
The electronic control monitors the signal from the meat probe after cooking begins. If the Main PCB does not receive the expected signal from the Upper Oven Meat Probe Sensor for more than one minute after cooking starts, the appliance may display F8.
What the F8 Error Code Means
LG identifies F8 as:
Upper Oven Meat Probe Error
The defining condition is:
No signal to the Main PCB from the Upper Oven Meat Probe Sensor for over one minute after cooking starts.
This means F8 is fundamentally a meat probe signal-circuit error.
The diagnostic path should focus on:
Upper Oven Meat Probe Sensor → Sensor Jack / Connections → Wiring → Main PCB
The error does not automatically prove that the meat probe itself has failed.
Common Causes
Possible areas requiring inspection include:
- Upper Oven Meat Probe Sensor
- Meat Probe Sensor Jack
- Loose probe connection
- Poor electrical contact
- Damaged connector
- Probe circuit wiring
- Main PCB connection
- Interrupted signal between the probe circuit and Main PCB
Because the code is triggered by the absence of the expected signal, the complete signal path should be considered during diagnosis.
What You Can Check
If F8 appears, note when and how the error occurs.
Useful observations include:
- Whether a meat probe is being used
- Whether the probe is fully inserted into its jack
- Whether F8 appears shortly after cooking begins
- Whether the code appears consistently when using the meat probe
- Whether the probe or jack appears physically damaged
- Whether the error occurs with a different compatible probe
- Whether the appliance was recently serviced
- The complete LG model number
The timing is particularly useful because the published F8 condition specifically involves a missing signal for over one minute after cooking starts.
Check the Upper Oven Meat Probe Sensor Jack
The direct F8 troubleshooting procedure specifically instructs technicians to check the:
Upper Oven Meat Probe Sensor Jack connections.
Inspect the jack and its connections for:
- Loose connection
- Probe not fully seated
- Physical damage
- Bent or damaged contact
- Contamination
- Poor terminal contact
- Damaged wiring behind the jack
A connection problem at the probe jack can interrupt the signal even if the probe itself is functional.
Check the Main PCB Connections
The source also specifically instructs technicians to check:
Main PCB connections.
The Main PCB must receive the meat probe sensor signal in order to monitor food temperature during probe-assisted cooking.
The basic signal path can be viewed as:
Meat Probe Sensor → Probe Jack → Wiring / Connections → Main PCB
A poor connection anywhere along this path can prevent the expected signal from reaching the control.
Probe vs. Connection Problem
F8 should not automatically lead to replacement of the Upper Oven Meat Probe Sensor.
A useful diagnostic distinction is:
Probe or sensor problem
→ The probe itself cannot provide the expected signal.
Connection or circuit problem
→ The probe may be functional, but the signal cannot reach the Main PCB because of the jack, wiring, or connector.
Inspecting the complete circuit helps avoid unnecessary component replacement.
Why the One-Minute Detection Period Matters
The F8 diagnostic description includes an important timing condition.
The error occurs when the Main PCB receives no signal from the Upper Oven Meat Probe Sensor for:
More than one minute after cooking starts.
This means F8 is not simply a generic indication that the probe is disconnected at any moment.
The control is specifically monitoring whether the expected sensor signal becomes available during the cooking cycle.
Check for Physical Damage
The meat probe system should also be visually inspected for physical problems.
Check for:
- Damaged probe
- Bent probe connector
- Damaged cable
- Loose jack
- Debris inside the probe jack
- Heat damage
- Damaged internal wiring
Physical damage can interfere with the electrical signal between the probe and electronic control.
No Resistance or Voltage Specification Is Provided
The direct F8 page does not provide a specific resistance or voltage specification for the Upper Oven Meat Probe Sensor.
Therefore, values from other LG temperature sensors should not be applied to F8.
If electrical testing of the meat probe is required, use the service information for the exact LG model and compatible probe.
What If the Connections Look Normal?
If the Upper Oven Meat Probe Sensor Jack and Main PCB connections appear normal but F8 continues, further diagnosis may be required.
The next areas to evaluate can include:
- Meat Probe Sensor
- Probe jack
- Wiring continuity
- Connector terminal contact
- Intermittent circuit interruption
- Main PCB probe-input circuit
Model-specific service information should be used for any electrical specifications not provided by the F8 source.
F8 vs. F18
F8 and F18 are closely related meat probe codes but apply to different oven sections.
F8 — Upper Oven Meat Probe Error
→ No signal from the Upper Oven Meat Probe Sensor for over one minute after cooking starts.
F18 — Lower Oven Meat Probe Error
→ No signal from the Lower Oven Meat Probe Sensor for over one minute after cooking starts.
The key distinction is:
F8 → Upper Oven
F18 → Lower Oven
This follows the same upper/lower pattern seen in several other LG range error-code pairs.
F8 Diagnostic Sequence
A practical diagnostic sequence is:
F8 displayed
→ Confirm the complete LG model number
→ Confirm whether the Upper Oven Meat Probe is being used
→ Inspect the meat probe for physical damage
→ Check that the probe is properly connected
→ Inspect the Upper Oven Meat Probe Sensor Jack
→ Check the jack connections
→ Inspect associated wiring
→ Check Main PCB connections
→ If the circuit appears normal but F8 returns, continue with model-specific probe and control diagnosis
This sequence follows the signal path from the meat probe toward the electronic control.
Can You Clear the F8 Code?
Disconnecting and restoring power may temporarily clear F8.
However, a reset cannot repair:
- Defective Meat Probe Sensor
- Damaged probe jack
- Loose electrical connection
- Broken wiring
- Persistent probe-signal circuit problem
If F8 repeatedly returns during probe-assisted cooking, the Upper Oven Meat Probe circuit should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F8 repeatedly returns
- The meat probe is not detected
- The probe and jack appear physically normal but the error continues
- Internal wiring requires inspection
- Main PCB connections require access
- Electrical diagnosis of the probe circuit is necessary
A technician can isolate the probe, jack, wiring, and control circuit to determine where the sensor signal is being interrupted.
Key Point
F8 indicates an Upper Oven Meat Probe Error.
The defining condition is:
No signal to the Main PCB from the Upper Oven Meat Probe Sensor for over one minute after cooking starts.
The direct troubleshooting procedure is:
Check Main PCB connections and Upper Oven Meat Probe Sensor Jack connections.
The source provides no resistance or voltage specification, so values from other LG sensors should not be applied to F8.
F9 — No Heat Error (Upper Oven)
The F9 error code usually indicates that the Upper Oven is not heating as expected in an LG range or oven.
The electronic control monitors how quickly the oven temperature rises after cooking begins. If the starting temperature is 130°F or lower, the oven door is closed, and the temperature does not increase by more than 10°F within five minutes, the appliance may display F9.
What the F9 Error Code Means
For most LG ranges and ovens:
F9 = No Heat Error (Upper Oven)
The detection conditions are:
- Starting oven temperature is 130°F or less
- Oven door is closed
- Cooking has started
- Oven temperature does not increase by more than 10°F compared with the starting temperature within 5 minutes
This allows the control to detect a heating system that has been activated but is not producing the expected temperature rise.
Important Model Exception
Several older LG electric ranges use F9 differently.
The affected models are:
- LRE3012
- LRE30451
- LRE30453
- LRE30757
For these models:
F9 = Oven Too Hot
The source directs diagnosis to the F6 Oven Too Hot troubleshooting procedure.
Therefore:
LRE3012 / LRE30451 / LRE30453 / LRE30757 → Oven Too Hot
All other models → Upper Oven Not Heating
Always confirm the complete model number before troubleshooting F9.
Common Causes
F9 can involve different components depending on whether the appliance uses electric or gas heating.
Possible areas requiring diagnosis include:
- Main PCB connections
- Temperature probe connections
- Oven temperature probe
- Thermostat
- Heating element
- Element wiring or connections
- Missing element voltage
- Heating element that opens under load
- Gas oven igniter
- Gas valve
- Ignition circuit
- Associated wiring and connectors
The correct diagnostic path depends heavily on whether the range is electric or gas.
What You Can Check
If F9 appears, note how the Upper Oven behaves.
Useful observations include:
- Whether the oven produces any heat
- Whether it heats slightly but fails to preheat
- Whether F9 appears about five minutes after cooking begins
- Whether Bake and Broil behave differently
- Whether the oven is gas or electric
- Whether the oven door closes normally
- Whether the appliance was recently serviced
- Whether the problem began after an electrical interruption
- The complete LG model number
The model number is especially important because the four older models use F9 for an entirely different condition.
Check Main PCB and Temperature Probe Connections
The direct F9 troubleshooting procedure first instructs technicians to check:
- Main PCB connections
- Temperature probe connections
Inspect for:
- Loose connectors
- Damaged wiring
- Poor terminal contact
- Backed-out terminals
- Heat-damaged connections
- Broken conductors
- Connectors that are not fully seated
The control needs accurate temperature feedback to determine whether the Upper Oven is heating correctly.
Check the Oven Temperature Probe
The temperature probe should also be evaluated as part of F9 diagnosis.
If the probe provides inaccurate temperature information, the control may incorrectly determine how much the oven temperature has increased.
Because F9 depends on the measured temperature change during the first five minutes, reliable temperature feedback is essential.
Use the appropriate model-specific specifications when electrically testing the temperature probe.
Check the Thermostat
The F9 source specifically instructs technicians to check the thermostat for continuity.
If the thermostat has no continuity, it is open. According to the source, the open thermostat should be replaced to restore voltage to the heating element.
A simplified path is:
Thermostat has continuity
→ Continue diagnosing the heating circuit.
Thermostat is open
→ The heating element may not receive the voltage required for operation.
Resistance and continuity testing should be performed with power disconnected.
Electric Oven — Check Heating Element Connections
For an electric oven, inspect the connections at:
- Main PCB
- Heating elements
The source specifically recommends checking for loose or damaged connections and reseating them as necessary.
A poor connection can interrupt the high-current heating circuit and prevent the oven from producing the expected temperature increase.
Electric Oven — Check Element Resistance
The direct F9 procedure also instructs technicians to check the heating elements for proper resistance.
An electrically open or otherwise abnormal element may be unable to produce heat.
The F9 page does not provide one universal element resistance value, so the correct specification should be obtained from the service information for the exact LG model.
Electric Oven — Check for 240 VAC
The F9 source specifically references 240 VAC at the heating element during diagnosis.
If the element has proper resistance and receives approximately 240 VAC, but the oven still does not heat and continues displaying the error, additional testing is required.
Live voltage testing involves potentially lethal voltage and should only be performed by a qualified technician using appropriate procedures.
Electric Oven — Check Element Current Draw
The source provides an additional diagnostic step when:
- Element resistance is correct
- Approximately 240 VAC is available
- Oven still does not heat
In this situation, use an amp clamp on the element leads to confirm whether the heating element is actually drawing current.
If the element does not draw current even though the other checks appear correct, the source notes that the element may be opening under load and may require replacement.
This is important because a heating element can sometimes appear normal during a static resistance test but fail when energized.
Gas Oven — Check the Ignition System
Gas models require a different diagnostic path.
The F9 source explains that for gas units displaying F9 or F19, the control needs to see approximately 3.3 amps before the gas valve will open.
The published specifications include:
Igniter resistance: approximately 45–400 Ω
Igniter current: approximately 3.1–3.3 amps
Gas valve resistance: approximately 1–3 Ω
These specifications are specifically associated with the gas oven ignition diagnostic information on the F9 page.
Gas Oven — Igniter and Gas Valve Operation
The gas valve is wired in series with the igniter (glow bar).
When 120 VAC is applied, the igniter requires a minimum of approximately 116 VAC, leaving about 4 volts to operate the gas valve. The source also states that the igniter remains energized while the burner is operating.
The published minimum ignition reference is:
116 VAC minimum and approximately 3.3 amps
This makes igniter current draw particularly important when diagnosing a gas oven that does not heat.
Why Igniter Current Matters
A gas oven igniter can glow visibly without necessarily drawing enough current to allow the gas valve to operate correctly.
For the F9/F19 gas diagnostic information, the source indicates that approximately 3.3 amps must be detected before the gas valve opens.
Therefore:
Igniter glows ≠ Ignition system necessarily operating correctly
Current draw is an important diagnostic measurement.
Electric vs. Gas F9 Diagnosis
The F9 diagnostic path changes substantially depending on the appliance type.
Electric Range
Check:
- Main PCB connections
- Temperature probe
- Thermostat continuity
- Heating element connections
- Element resistance
- Approximately 240 VAC
- Element current draw when necessary
Gas Range
Check:
- Temperature feedback
- Igniter
- Igniter resistance: 45–400 Ω
- Igniter current: 3.1–3.3 A
- Gas valve resistance: 1–3 Ω
- Ignition circuit operation
This distinction should be made before performing component-level diagnosis.
F9 vs. F7
The older-model exception creates an important relationship between F7 and F9.
For LRE3012, LRE30451, LRE30453, and LRE30757:
F7 → Oven Not Heating
For those models, the F7 page directs technicians to the F9 troubleshooting procedure.
For most other models:
F7 → Upper Convection Fan Error
F9 → Upper Oven No Heat Error
This is another reason the model number should be checked before interpreting the displayed code.
F9 vs. F19
F9 and F19 are related Upper/Lower Oven heating codes in applicable LG models.
F9 → Upper Oven Not Heating
F19 → Lower Oven Not Heating
The F9 source specifically references both F9 and F19 when discussing gas oven burner ignition diagnosis.
This supports treating the two codes as related heating-system faults while preserving their Upper/Lower Oven distinction.
F9 Diagnostic Sequence
A practical diagnostic sequence is:
F9 displayed
→ Confirm the complete LG model number
→ Check whether it is LRE3012, LRE30451, LRE30453, or LRE30757
→ For those models, diagnose Oven Too Hot using the F6 procedure
→ For other models, confirm Upper Oven no-heat symptoms
→ Check Main PCB and Temperature Probe connections
→ Check the temperature probe
→ Identify whether the appliance is electric or gas
Electric:
→ Check thermostat continuity
→ Inspect element connections
→ Check element resistance
→ Check approximately 240 VAC when appropriate
→ Check element current draw if resistance and voltage appear correct
Gas:
→ Evaluate the igniter and gas valve circuit
→ Check igniter resistance/current
→ Check gas valve resistance
→ Verify proper ignition-system operation
Can You Clear the F9 Code?
Disconnecting and restoring power may temporarily clear F9.
However, a reset cannot repair:
- Open thermostat
- Failed heating element
- Element that opens under load
- Poor electrical connection
- Igniter problem
- Gas valve circuit problem
- Temperature probe problem
- Persistent heating-control fault
If F9 returns, the Upper Oven heating system should be diagnosed.
When Professional Diagnosis Is Recommended
Professional diagnosis is recommended when:
- F9 repeatedly returns
- The Upper Oven does not heat
- The oven heats very slowly
- An electric element requires 240 VAC testing
- Current draw needs to be measured
- A gas igniter or gas valve requires diagnosis
- Internal wiring or electronic controls require testing
Both 240 VAC electric heating circuits and gas ignition systems present serious hazards and should be serviced using appropriate professional procedures.
Key Point
For most LG ranges and ovens:
F9 = No Heat Error (Upper Oven)
The control detects the condition when the starting temperature is 130°F or less, the door is closed, and the oven temperature fails to increase by more than 10°F within five minutes after cooking begins.
For older LRE3012, LRE30451, LRE30453, and LRE30757 models:
F9 = Oven Too Hot → use the F6 diagnostic procedure.
F9 diagnosis should then be divided by appliance type: electric heating circuit or gas burner ignition system.
HS — Hot Surface Indicator
The HS message is not an error code. It is a normal Hot Surface Indicator used on LG ranges and cooktops to warn that the cooking surface is still hot.
HS may remain displayed after a burner or cooking zone has been turned off because residual heat is still present on the cooktop surface.
What the HS Message Means
HS = Hot Surface
The message indicates that the cooktop surface is still hot enough to require caution.
This is a normal safety feature rather than an indication that the appliance has malfunctioned.
The HS indicator may remain visible even though:
- The cooking zone has been turned off
- Cooking has finished
- The burner is no longer actively heating
- The cooktop controls are otherwise operating normally
Residual heat can remain in the cooking surface for some time after use.
Is HS an Error Code?
No.
HS is a status and safety indicator, not a fault code.
You normally do not need to:
- Reset the appliance
- Disconnect power
- Replace a component
- Schedule a repair
- Perform electrical diagnostics
If the cooktop was recently used and HS is displayed, allow the cooking surface to cool naturally.
Why HS Appears After the Burner Is Turned Off
Turning off a cooking zone stops active heating, but it does not instantly cool the cooktop surface.
Heat stored in the cooking surface, cookware, and surrounding components takes time to dissipate.
The HS indicator warns users that the surface may still be hot even though the burner itself has been switched off.
This helps reduce the risk of accidentally touching a hot cooking area.
What Should You Do When HS Appears?
If HS appears after cooking:
- Leave the cooking surface uncovered and allow it to cool.
- Avoid touching the indicated cooking area.
- Keep heat-sensitive objects away from the surface.
- Do not assume the surface is safe to touch simply because the burner is off.
- Wait for the HS indicator to disappear.
Under normal operation, the indicator should clear automatically as the cooktop cools.
How Long Does HS Stay On?
The amount of time HS remains displayed can vary depending on how much heat remains in the cooking surface.
Cooling time can be affected by factors such as:
- How long the cooking zone was used
- Cooking temperature
- Cookware temperature
- Amount of residual heat
- Surrounding conditions
The important point is that HS should disappear automatically after the cooking surface has cooled sufficiently.
Can You Clear the HS Indicator?
Normally, there is no reason to manually clear HS.
Because HS represents a hot-surface condition, resetting the appliance simply to remove the message is unnecessary.
The appropriate response is:
Allow the cooktop to cool.
Once the surface reaches the appropriate temperature, the indicator should turn off automatically.
What If HS Stays On?
If the cooktop has been completely cool for an extended period but HS continues to display, the behavior may require further investigation.
Before assuming there is a fault:
- Make sure the cooking surface has fully cooled
- Confirm that no cooking zone is operating
- Allow additional cooling time
- Confirm the exact model number and normal indicator behavior for that model
If HS remains displayed when the cooktop is clearly cold, model-specific diagnosis may be appropriate.
What If HS Does Not Appear After Cooking?
Because HS serves as a hot-surface warning, unexpected indicator behavior may also deserve attention.
If the cooktop has been heavily heated but the expected Hot Surface Indicator never appears, consult the operating information for the exact LG model to confirm how its hot-surface indication is designed to function.
Different LG range and cooktop models may display status information differently.
HS vs. an Actual Error Code
It is important to distinguish HS from diagnostic fault codes such as F6, F9, or other F-series codes.
HS — Hot Surface Indicator
→ Normal safety/status message
→ Surface is still hot
→ Allow the cooktop to cool
F-series diagnostic code
→ May indicate an abnormal condition detected by the appliance
→ Troubleshooting may be required
Seeing HS by itself after cooking does not normally indicate that the appliance needs repair.
Do You Need Professional Repair for HS?
Normally, no.
If HS appears while the cooking surface is hot and disappears after it cools, the appliance is behaving as expected.
Professional diagnosis may be worth considering only if the indicator behaves abnormally, such as remaining displayed when the cooktop has been completely cold for an extended period.
Key Point
HS means Hot Surface. It is not an error code.
The indicator warns that the LG cooktop surface is still hot after use.
Do not touch the cooking surface while HS is displayed. Allow the cooktop to cool naturally. The indicator should disappear automatically once the surface has cooled sufficiently.
PF — Power Failure (Not an Error Code)
The PF message indicates that electrical power to the LG range or oven has been interrupted.
PF stands for:
Power Failure
This is not an error code and does not normally indicate that a component has failed. It is an informational message letting you know that the appliance experienced a loss or interruption of electrical power.
What the PF Message Means
LG displays PF when power has been interrupted to the appliance.
This can occur after situations such as:
- A household power outage
- A brief interruption in electrical service
- The range being unplugged
- Power being switched off at the circuit breaker
- Electrical service work
- Power being restored after the appliance was disconnected
If PF appears immediately after a known power interruption, the message is normally expected behavior.
Is PF an Error Code?
No.
PF is not an error code.
The message indicates that the appliance detected an interruption in its electrical power supply.
In most cases, PF by itself does not mean that the range requires repair.
How to Clear the PF Message
The published procedure for clearing PF is straightforward:
Press the ON/OFF control pad to reset the appliance.
After resetting the appliance:
Reset the clock to the correct time.
No component replacement or internal troubleshooting is normally required when PF follows a known power interruption.
Why the Clock May Need to Be Reset
A power interruption can cause the appliance’s clock setting to be lost or changed.
This is why the PF procedure includes resetting the clock after clearing the message.
After power is restored:
PF appears → Reset the control → Set the clock to the correct time
Once this is completed, the appliance should normally return to regular operation.
What If PF Appears After a Power Outage?
If your home recently experienced a power outage or brief electrical interruption, PF is normally expected.
Use the following sequence:
- Confirm that household power has been restored.
- Press the ON/OFF control pad to clear PF.
- Reset the clock to the correct time.
- Confirm that the range or oven operates normally.
If the message clears and does not return, no additional troubleshooting is usually necessary.
What If PF Keeps Returning?
A PF message that repeatedly returns without a known power outage may indicate that the appliance is experiencing repeated power interruptions.
Possible areas worth investigating can include:
- Household electrical supply
- Circuit breaker
- Appliance power connection
- Power cord or connection
- Intermittent loss of electrical power
PF itself does not identify which part of the electrical supply was interrupted.
If the message repeatedly returns, the goal should be to determine why power to the appliance is being interrupted.
PF After Using the Circuit Breaker
PF may also appear after power to the range has intentionally been switched off at the breaker.
For example:
Breaker OFF → Appliance loses power → Breaker ON → PF appears
This does not necessarily indicate a fault. The appliance is simply reporting that its power supply was interrupted.
Clear the message using the normal ON/OFF control procedure and reset the clock if necessary.
Does PF Mean the Main PCB Is Bad?
Not by itself.
PF only tells you that the appliance detected a power interruption.
It should not automatically be interpreted as:
- Failed Main PCB
- Failed heating element
- Failed temperature sensor
- Failed burner
- Internal appliance malfunction
If the range operates normally after PF is cleared, component-level diagnosis is generally unnecessary.
PF vs. an Actual Error Code
PF should be distinguished from diagnostic fault codes such as F6, F9, or other F-series codes.
PF — Power Failure
→ Power was interrupted
→ Not an error code
→ Reset using ON/OFF control
→ Reset the clock
Diagnostic error code
→ Appliance has detected an abnormal operating condition
→ Troubleshooting may be required
This distinction can prevent unnecessary repairs after a normal power outage.
PF vs. HS
PF and HS are both messages that users may mistake for LG error codes, but neither normally indicates a malfunction.
PF — Power Failure
→ Electrical power was interrupted.
HS — Hot Surface
→ Cooktop surface remains hot.
Both are informational/status messages rather than conventional diagnostic error codes.
Should You Reset the Circuit Breaker for PF?
The direct PF procedure does not instruct users to cycle the circuit breaker simply to clear the message.
Instead, the published procedure is:
Press the ON/OFF control pad to reset.
Then:
Reset the clock to the correct time.
If electrical power is already available and the appliance otherwise operates normally, repeatedly cycling the breaker should not be necessary just to remove PF.
When Professional Diagnosis May Be Needed
PF normally does not require professional service.
Further investigation may be appropriate if:
- PF repeatedly returns without known power outages
- The range repeatedly loses power
- The display turns on and off unexpectedly
- The appliance resets during cooking
- The circuit breaker repeatedly trips
- The range does not operate normally after power is restored
In these situations, the underlying issue is not simply the PF message—the repeated loss of power needs to be diagnosed.
Key Point
PF means Power Failure, and it is not an error code.
The message appears when electrical power to the appliance has been interrupted.
The published reset procedure is:
Press the ON/OFF control pad to clear PF → Reset the clock to the correct time.
If PF appears after a known power outage and disappears after the reset, the appliance is normally behaving as expected.
Sb — Sabbath Mode (Not an Error Code)
The Sb message is not an error code. It indicates that Sabbath Mode has been activated on the LG range or oven.
Sabbath Mode changes how several oven controls operate and is designed for use during the Jewish Sabbath and holidays.
If Sb appears on the display and the oven otherwise seems unresponsive to certain controls, the appliance may simply be operating in Sabbath Mode.
What the Sb Message Means
Sb = Sabbath Mode
When Sabbath Mode is active:
- The oven temperature cannot be changed
- Timer functions are disabled
- Light controls are disabled
- Alarm functions are disabled
- Sabbath Mode is available only when the oven is in Bake mode
If the oven light was already on when Sabbath Mode was activated, it will remain on.
These operating restrictions are intentional and do not normally indicate a malfunction.
Is Sb an Error Code?
No.
Sb is a status message, not an error code.
It tells you that the oven has been placed into Sabbath Mode.
This distinction is important because users may see Sb on the display and assume the appliance has developed an electronic or control-panel fault.
Normally, no repair is required.
Why Does the Oven Seem Unresponsive?
Some normal oven functions are intentionally restricted while Sabbath Mode is active.
For example, you may notice that:
- The temperature cannot be adjusted
- The timer does not operate normally
- Audible alarms are disabled
- Oven light controls do not respond normally
These symptoms can appear unusual if Sabbath Mode was activated accidentally, but they are part of the mode’s intended operation.
How to Turn Off Sabbath Mode
The procedure for disabling Sabbath Mode depends on the LG model.
The source specifically notes that its examples are not all-inclusive and recommends checking the owner’s manual for the exact model.
Two examples are provided.
LSEL6333 and LSEL633CF Models
For the LSEL6333 and LSEL633CF model families, Sabbath Mode is activated during Bake operation by pressing and holding Start Time for 3 seconds.
When activated:
“Sb” appears on the display.
To stop Sabbath Mode:
Press and hold Start Time for 3 seconds.
To cancel the Bake function completely:
Turn the oven mode knob to OFF.
LSEL6331 Models
For the LSEL6331 model family, the control procedure is different.
Sabbath Mode is activated by pressing and holding:
Clock for 3 seconds
When Sabbath Mode is active, Sb appears on the display.
To turn Sabbath Mode off:
Press and hold Clock for 3 seconds.
To cancel Bake:
Set the oven mode knob to OFF.
Why the Model Number Matters
There is no single Sabbath Mode cancellation procedure that should be assumed for every LG range.
Depending on the model, the relevant control may differ.
Therefore, if the procedures above do not match your control panel:
- Find the complete LG model number.
- Check the owner’s manual for that model.
- Find the Sabbath Mode instructions.
- Follow the model-specific cancellation procedure.
Do not assume that a button combination from another LG range will work on your appliance.
Can Sabbath Mode Be Activated Accidentally?
Yes. A user unfamiliar with the control-panel functions may activate Sabbath Mode without realizing what happened.
The combination of:
Sb on the display + unavailable controls
can make the appliance appear to have developed a fault.
Before troubleshooting the control board or scheduling repair, confirm whether Sabbath Mode is active.
What Happens to the Oven Light?
The source provides an important detail about the oven light.
If the oven light is already on when Sabbath Mode is activated, it will remain on.
Because normal light-control functionality is restricted in Sabbath Mode, this behavior should not automatically be interpreted as a failed light switch or control-panel problem.
Can the Temperature Be Changed in Sabbath Mode?
No.
The source specifically states that the temperature cannot be changed while the oven is in Sabbath Mode.
If you need to return to normal temperature adjustment, exit Sabbath Mode using the procedure specified for your LG model.
Does Sb Require Professional Repair?
Normally, no.
If Sb disappears after Sabbath Mode is properly canceled and normal oven controls return, the appliance is operating as expected.
Professional diagnosis may be appropriate if:
- Sb cannot be cleared using the correct model-specific procedure
- The oven remains unresponsive after Sabbath Mode is disabled
- The control panel behaves abnormally outside Sabbath Mode
- Other diagnostic error codes appear
- The oven does not return to normal operation
In these situations, confirm the exact model and owner’s manual procedure before assuming an appliance failure.
Sb vs. HS and PF
Sb belongs to the same general category of display messages that users can easily mistake for error codes.
Sb — Sabbath Mode
→ Sabbath Mode is active
→ Not an error code
HS — Hot Surface
→ Cooking surface remains hot
→ Not an error code
PF — Power Failure
→ Appliance experienced a power interruption
→ Not an error code
Including these messages in an LG error-code guide is useful because users commonly search for them as though they were faults.
Sb Diagnostic Sequence
If Sb appears:
Sb displayed
→ Recognize that Sabbath Mode is active
→ Confirm the complete LG model number
→ Check the model-specific Sabbath Mode procedure
→ Use the appropriate button/control to disable the mode
→ Return the oven to normal operation
→ If Sb cannot be cleared, consult the owner’s manual for the exact model
For the models specifically documented by the source:
LSEL6333 / LSEL633CF → Hold Start Time for 3 seconds
LSEL6331 → Hold Clock for 3 seconds
Key Point
Sb means Sabbath Mode. It is not an error code.
While Sabbath Mode is active:
Temperature changes are unavailable
Timer functions are disabled
Light controls are disabled
Alarm functions are disabled
Sabbath Mode is available only while the oven is in Bake mode.
The method used to turn Sabbath Mode off varies by model, so use the procedure for the exact LG range rather than assuming one button combination works for every appliance.
On This Page
- How LG Oven & Range Error Codes Work
- What an LG Oven & Range Error Code Can Tell You
- An Error Code Does Not Always Mean a Part Has Failed
- Why LG Oven & Range Error Codes Can Vary by Model
- What to Do When an Error Code Appears
- Can You Clear an LG Oven & Range Error Code?
- When an Error Code Requires Professional Diagnosis
- Find Your LG Oven & Range Error Code
- CF1 — Left Front Induction Burner Temperature Sensor Error
- CF2 — Left Rear Induction Burner Temperature Sensor Error
- CF3 — Right Front Induction Burner Temperature Sensor Error
- CF4 — Right Rear Induction Burner Temperature Sensor Error
- CF5 — Left Inverter Board IGBT Error
- CF6 — Right Inverter Board IGBT Error
- CF7 — Communication Error Between Cooktop Main PCB & Left Inverter PCB
- CF8 — Communication Error Between Cooktop Main PCB & Right Inverter PCB
- CF9 — Flex Top Sensor Failure
- CFA — Over Current Error
- CFC — Over Voltage Error
- CFE — Blower Fan Error
- CFF — Box Fan Error
- F1 — Upper Oven Thermistor Error
- F10 — Upper Oven Door Locking System Failure
- F11 — Lower Oven Door Locking System Failure
- F16 — Lower Oven Too Hot
- F17 — Lower Convection Fan Error
- F18 — Lower Oven Meat Probe Error
- F19 — Lower Oven Temperature Sensor Error
- F2 — Lower Oven Temperature Sensor Error
- F20 — Lower Oven Door Locking System Failure
- F21 — Right Steam Sensor Open / Steam Sensor Failure
- F22 — Left Steam Sensor Open / Steam Sensor Failure
- F24 — Lower Oven Meat Probe Shorted Error
- F25 — Lower Oven Heating Error
- F27 — Cooling Fan Stalled or Locked During Self Clean
- F3 — Touch Pad Sensor Key Error
- F33 — Front Induction Burner Temperature Sensor Error
- F34 — Rear Induction Burner Temperature Sensor Error
- F36 — Inverter Board IGBT Error
- F38 — Communication Error Between Cooktop Main PCB & Inverter PCB
- F4 — Lower Oven Thermistor Error
- F42 — Over Voltage Error
- F45 — Box Fan Error
- F46 — IH (Induction Heater) Blow Fan Error
- F5 — Lower Oven Thermistor Error
- F51 — Griddle Sensor Open Error
- F52 — Griddle Sensor Shorted Error
- F56 — Griddle Is Too Hot Error
- F59 — Griddle Not Heating Error
- F6 — Upper Oven Too Hot
- F62 — Sous Vide Temperature Sensor Error
- F69 — Sous Vide Not Heating Error
- F7 — Upper Convection Fan Error
- F8 — Upper Oven Meat Probe Error
- F9 — No Heat Error (Upper Oven)
- HS — Hot Surface Indicator
- PF — Power Failure
- Sb — Sabbath Mode
Oven & Range Repair Throughout the Denver Metro Area
Need Professional Oven & Range Repair?
If your LG oven or range isn’t heating properly, won’t reach the set temperature, has ignition or door lock problems, or keeps displaying an error code, the problem may require professional diagnostics.
Mint Appliance Repair provides professional oven and range diagnosis and repair throughout the Denver metro area.
Same-day appointments
Upfront pricing
90-day warranty on parts and labor
Denver metro experts
TROUBLESHOOTING BY PROBLEM
- Refrigerator Not Cooling
- Dishwasher Not Draining
- Washer Won’t Drain
- Appliance Making Noise
- Dryer Not Heating
- Appliance Leaking Water
- Oven Not Heating
- Appliance Won’t Turn On
FEATURED REPAIR GUIDES
Why Is My Refrigerator Not Cooling?
Common causes include dirty condenser coils, failed fans, defrost problems, sensors, and sealed-system failures.
Why Won’t My Washer Drain?
Learn what causes drainage issues and how to diagnose pumps, hoses, and filters.
Why Is My Dryer Not Heating?
Find out the most common reasons why your dryer doesn’t heat and how to fix them.
Oven Not Heating? Top 6 Causes
From bad igniters to control boards—here’s how to identify the problem.