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Error code reference

LG Cooktop Error Code F5

Front right no feedback (no signal feedback from front right cooking zone).

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Front right no feedback (no signal feedback from front right cooking zone).

First step from the service manual

Check connector CN01 on the front IH module.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F5 means on a LG cooktop

The F5 error code on an LG induction cooktop indicates a loss of signal feedback from the front right cooking zone. In induction cooktop systems, each cooking zone relies on continuous communication between the main control board and the individual induction heating (IH) module assigned to that zone. The front right IH module is expected to send feedback signals confirming its operational status, power output, and temperature data. When that feedback signal is absent or interrupted, the control board flags F5 and typically disables the affected zone to prevent unsafe operation.

The front IH module connects to the control system through a dedicated connector, designated CN01, located on the front IH module itself. This connector carries both power and signal lines between the module and the main board. A loose, corroded, or damaged connector at CN01 is the most frequent point of failure and the recommended first inspection point. Beyond the connector, the fault can originate from a failure within the IH module's internal circuitry, a damaged wiring harness between CN01 and the main board, or a defective main control board that is no longer processing the feedback signal correctly.

Diagnosing F5 requires a systematic approach starting at CN01. The connector should be inspected for secure seating, bent or corroded pins, and any signs of heat damage or melted plastic. If the connector checks out, continuity testing on the signal wiring harness is the next step. If wiring is intact, the IH module itself should be evaluated for internal failure. Replacing the IH module or the main control board are the final steps if no wiring or connector fault is found.

Source: manufacturer service documentation.

Common causes of F5

  1. 01

    Loose or disconnected connector CN01

    Wiring / connection

    The CN01 connector on the front IH module can work loose over time due to vibration or heat cycling. Reseating the connector firmly is the first and most commonly successful fix.

  2. 02

    Corroded or damaged connector pins

    Part replacement

    Moisture or heat exposure can corrode the pins inside the CN01 connector, degrading the signal path. Inspect the pins visually and clean or replace the connector if corrosion or burn marks are present.

  3. 03

    Damaged wiring harness

    Part replacement

    The wiring harness running between the CN01 connector and the main control board can develop breaks or shorts from pinching or heat exposure. Continuity testing along the harness will confirm whether a break exists.

  4. 04

    Failed front right IH module

    Part replacement

    Internal component failure within the front right induction heating module can cause it to stop sending feedback signals entirely. If the connector and wiring test good, the IH module itself is likely defective and needs replacement.

  5. 05

    Defective main control board

    Part replacement

    If the IH module, connector, and wiring all check out correctly, the main control board may have failed and is no longer able to receive or process the feedback signal from the front right zone.

See the test procedure for each cause

Frequently asked questions about F5

What does F5 mean on a LG cooktop?
F5 on an LG cooktop means the control system is receiving no signal feedback from the front right cooking zone's induction heating module. The cooktop detects that communication with that zone has been lost and disables it to prevent unsafe operation. The first place to check is connector CN01 on the front IH module, which is the most common source of the fault.
Can I fix the F5 error myself?
If the cause is a loose CN01 connector, reseating it is a straightforward repair that a confident DIYer can perform after unplugging the cooktop and accessing the underside of the unit. However, if the connector is damaged, the wiring harness is broken, or the IH module or control board has failed, those repairs involve handling high-voltage components and are best handled by a qualified appliance technician.
Is it safe to keep using the cooktop with an F5 error?
The front right zone will be disabled when F5 is active, so you will not be able to use that burner. The remaining zones may continue to function, but operating the cooktop with an unresolved fault is not recommended. It is best to diagnose and repair the underlying cause before relying on the unit for regular cooking.
Will resetting the cooktop clear the F5 error?
Powering the cooktop off at the circuit breaker for a minute and restoring power may temporarily clear the F5 code if the fault was caused by a transient signal issue. However, if there is an actual hardware problem such as a loose connector, damaged wiring, or a failed IH module, the error will return once the cooktop tries to operate the front right zone again. A reset is not a substitute for diagnosing the root cause.
How much does it cost to repair an F5 error on an LG cooktop?
If the fix is simply reseating the CN01 connector, your cost may be minimal, covering only a service call fee, which typically ranges from $75 to $150. If the IH module needs replacement, parts and labor combined can range from $200 to $450 depending on your location and the specific model. A main control board replacement is generally the most expensive repair, often falling in the $300 to $600 range with labor included.

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