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Error code reference

LG Cooktop Error Code F8

Rear left no feedback (no signal feedback from rear left cooking zone).

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Rear left no feedback (no signal feedback from rear left cooking zone).

First step from the service manual

Check connector CN01 on the rear IH module.

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

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What F8 means on a LG cooktop

The F8 error code on an LG induction cooktop indicates a loss of signal feedback from the rear left cooking zone. In induction cooktop systems, each cooking zone is controlled by a dedicated IH (induction heating) module. This module continuously sends and receives feedback signals to confirm that the zone is operating correctly. When the control system fails to receive a response from the rear left zone's IH module, it flags the F8 fault and typically disables that zone to prevent unsafe or uncontrolled operation.

The rear IH module communicates with the main control board through a connector designated CN01. A fault at this connector is the primary place to begin diagnosis. Loose, corroded, or damaged pins at CN01 can interrupt the feedback signal entirely, causing the error to appear even when the IH module itself is fully functional. This is why inspecting CN01 is the recommended first diagnostic step before replacing any components.

If the CN01 connector checks out and the connection is secure and clean, the fault likely originates within the rear left IH module itself. Internal component failure within the module, such as a damaged feedback circuit or a failed gate driver, can prevent the module from generating the expected signal. Wiring harness damage between the module and the main control board is also a possible contributor. Systematic inspection of the connector, wiring, and then the module in that order will help isolate the root cause efficiently.

Source: manufacturer service documentation.

Common causes of F8

  1. 01

    Loose or disconnected CN01 connector

    Wiring / connection

    The connector CN01 on the rear IH module may have worked loose over time due to vibration or heat cycling. Reseating the connector firmly is the first step and can resolve the error if no other damage is present.

  2. 02

    Corroded or damaged connector pins at CN01

    Part replacement

    Moisture or heat exposure can cause pin corrosion or physical damage at CN01, breaking the feedback signal path. Inspect each pin closely for discoloration, bending, or oxidation and clean or replace the connector as needed.

  3. 03

    Failed rear left IH module

    Part replacement

    If the connector is intact and secure, the rear left IH module itself may have an internal failure in its feedback circuit. A failed module will need to be replaced to restore normal operation.

  4. 04

    Damaged wiring harness between IH module and main control board

    Part replacement

    The wiring harness connecting the rear IH module to the main control board can develop breaks or shorts, interrupting the feedback signal. Inspect the harness along its full length for pinching, burns, or severed wires.

  5. 05

    Main control board failure

    Part replacement

    In less common cases, the main control board may fail to read or process the feedback signal from the rear left zone even when the module and wiring are functioning correctly. This is typically diagnosed after all other components have been ruled out.

See the test procedure for each cause

Frequently asked questions about F8

What does F8 mean on a LG cooktop?
The F8 error code means the cooktop's control system is not receiving any signal feedback from the rear left induction cooking zone. The cooktop monitors each zone through its dedicated IH module, and when communication is lost, it displays F8 and disables the affected zone. The issue typically points to a wiring or connector problem at the rear IH module, specifically at connector CN01.
Will resetting the cooktop clear the F8 error?
A reset may temporarily clear the F8 code, but if the underlying fault is still present, the error will return when the cooktop tries to use the rear left zone again. Resetting is not a fix on its own. The connector, wiring, and IH module need to be physically inspected and repaired to resolve the fault permanently.
Is it safe to keep using my LG cooktop with an F8 error?
The rear left cooking zone will be disabled while the F8 error is active, so you should not attempt to use that specific burner. The remaining zones may still function, but continued use of the cooktop in a faulted state is not recommended. It is best to have the unit inspected and repaired before relying on it for regular cooking.
How do I fix the F8 error on my LG cooktop?
Start by checking connector CN01 on the rear IH module to ensure it is fully seated and free of corrosion or damaged pins. If the connector is secure and undamaged, inspect the wiring harness between the IH module and the main control board for any breaks or shorts. If the wiring and connector are both in good condition, the rear left IH module itself likely needs to be replaced. A qualified appliance technician can perform these checks safely.
How much does it cost to repair an F8 error on a LG cooktop?
Repair costs vary depending on whether the fix is a simple connector reseating or requires a component replacement. A connector cleaning or reseating is typically part of a standard diagnostic service call, which can run anywhere from $75 to $150. If the rear IH module needs replacement, total parts and labor costs can range from $150 to $400 or more depending on the specific model and local labor rates.

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