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Error code reference

LG Oven Error Code F-3

Touch sensor key error

LG codesLG oven codes

Touch sensor key error — touch sensor key has an error for 60 seconds or more.

First step from the service manual

Check the connection between KEY PCB CN01 and MAIN PCB CN603.

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

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What F-3 means on a LG oven

The F-3 error code on an LG oven indicates a touch sensor key error, meaning the control panel's touch sensor circuitry has been detecting a fault condition continuously for 60 seconds or longer. The touch keypad system relies on a dedicated KEY PCB (printed circuit board) that reads capacitive or resistive input from the touch surface and communicates that data to the MAIN PCB. When the MAIN PCB receives abnormal or uninterrupted signals from the KEY PCB for a full minute, it logs and displays the F-3 fault to alert the technician or user that the input system is compromised.

The most common point of failure in this circuit is the wiring harness connecting the KEY PCB at connector CN01 to the MAIN PCB at connector CN603. A loose, corroded, or damaged connector at either end can cause signal irregularities that the MAIN PCB interprets as a sustained key error. Beyond the connector, the KEY PCB itself may have failed due to moisture intrusion, heat damage, or component degradation on the board. In some cases, the touch surface overlay can become contaminated or physically damaged, causing a specific key zone to register as continuously pressed.

Diagnosis should begin by inspecting the CN01-to-CN603 harness for secure seating, bent pins, and visible wire damage before condemning either board. If the connector and harness check out, the KEY PCB is the next most likely failed component, followed by the MAIN PCB if replacing the KEY PCB does not resolve the fault.

Source: manufacturer service documentation.

Common causes of F-3

  1. 01

    Loose or faulty harness connector between KEY PCB and MAIN PCB

    Wiring / connection

    The connector at KEY PCB CN01 or MAIN PCB CN603 may be partially unseated, corroded, or have a bent pin, interrupting proper signal communication. Inspect both connectors visually and reseat them firmly to confirm a secure connection.

  2. 02

    Failed or damaged KEY PCB

    Part replacement

    The KEY PCB itself can fail due to heat exposure, moisture damage, or component failure on the board, causing it to output a continuous or erroneous signal. If the harness and connectors test good, the KEY PCB is the next component to replace.

  3. 03

    Contaminated or stuck touch surface

    Wiring / connection

    Grease, liquid, or debris on the touch panel surface can cause a key zone to register as permanently activated, triggering the 60-second error threshold. Clean the touch surface thoroughly and check whether the error clears.

  4. 04

    Damaged wiring harness between the two boards

    Part replacement

    The wire harness running between the KEY PCB and MAIN PCB can develop breaks, pinches, or shorts, especially if it is routed near a heat source. Inspect the full length of the harness for visible damage or continuity faults.

  5. 05

    Failed MAIN PCB

    Part replacement

    If the KEY PCB, harness, and connectors all test properly, the MAIN PCB may be misinterpreting the incoming signals due to internal component failure. MAIN PCB replacement is typically a last resort after all other causes have been ruled out.

See the test procedure for each cause

Frequently asked questions about F-3

What does F-3 mean on a LG oven?
The F-3 code on an LG oven indicates a touch sensor key error. Specifically, the oven's control system has detected an abnormal or continuous signal from the touch keypad for 60 seconds or more. This points to a problem in the touch panel circuitry, the wiring connecting the KEY PCB to the MAIN PCB, or the boards themselves.
Can I fix the F-3 error on my LG oven myself?
Some causes of F-3 are DIY-friendly, such as reseating a loose connector at KEY PCB CN01 or MAIN PCB CN603, or cleaning a contaminated touch surface. However, replacing the KEY PCB or MAIN PCB involves working inside the oven's control cavity and requires comfort with electronics and appliance disassembly. If you are not experienced with appliance repair, a qualified technician is recommended for board-level repairs.
Is it safe to use my LG oven when the F-3 error is showing?
The F-3 error indicates the touch control system is not operating reliably, which means the oven may not respond correctly to input commands. It is best to avoid using the oven until the fault is resolved, as unpredictable control behavior can create safety concerns. Power the oven off at the breaker until the issue is diagnosed and repaired.
Will resetting my LG oven clear the F-3 error?
Resetting the oven by cutting power at the circuit breaker for a few minutes may temporarily clear the F-3 code, but the error will return if the underlying hardware fault is still present. A reset is a useful first step to confirm whether the fault is intermittent, but it is not a permanent fix. The connector, harness, and KEY PCB should still be inspected after a reset.
How much does it cost to repair an F-3 error on an LG oven?
Repair costs vary depending on the failed component. If only a connector reseat or cleaning is needed, there may be no parts cost at all, though a service call fee typically ranges from $75 to $150. Replacing the KEY PCB generally adds $50 to $200 in parts, while a MAIN PCB replacement can add $150 to $400 or more depending on the specific model. Getting a diagnostic estimate before authorizing repairs is always advisable.

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