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Error code reference

LG Cooktop Error Code F3

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

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Front left no feedback (no signal feedback from front left 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 F3 means on a LG cooktop

The F3 error code on an LG induction cooktop indicates that the control system is receiving no signal feedback from the front left cooking zone. In induction cooktops, each cooking zone contains an IH (induction heating) module that continuously communicates operational status back to the main control board. When this feedback loop is broken or absent, the control board cannot confirm whether the front left zone is functioning, and it triggers the F3 code to protect both the user and the appliance from operating in an unknown state.

The front left IH module sends feedback through a dedicated connector, identified as CN01, on the front IH module board. This feedback signal typically carries information about coil status, temperature sensing, and operational confirmation. A failure at this connector is the most common entry point for diagnostics because connector issues, including loose pins, corrosion, or damaged wiring harnesses, can interrupt the signal without any actual failure of the induction coil or drive circuitry itself.

Beyond the connector, the fault can originate from a failed front IH module, a damaged wiring harness between the module and the main board, or a failure in the main control board's ability to receive and interpret the feedback signal. Thermal stress, moisture intrusion, and physical damage from impact or vibration are common environmental factors that contribute to these failures over time.

Source: manufacturer service documentation.

Common causes of F3

  1. 01

    Loose or disconnected CN01 connector

    Wiring / connection

    The CN01 connector on the front IH module is the first component to inspect. Vibration, heat cycling, or improper reassembly after a previous repair can cause this connector to seat poorly or disengage, cutting off the feedback signal entirely.

  2. 02

    Damaged or corroded wiring harness

    Part replacement

    The wiring harness running between the front IH module and the main control board can develop broken conductors, burned insulation, or corroded terminals. Inspect the full length of the harness for visible damage, discoloration, or pin-level corrosion at both ends.

  3. 03

    Failed front IH module

    Part replacement

    If the CN01 connector and wiring harness check out, the front IH module itself may have failed internally. A failed module will not generate any feedback signal regardless of connection quality, and the board will need to be replaced.

  4. 04

    Failed main control board

    Part replacement

    In some cases the main control board loses the ability to receive or process the feedback signal from the front left zone even when the IH module and wiring are intact. This is a less common cause but should be considered after other components are ruled out.

See the test procedure for each cause

Frequently asked questions about F3

What does F3 mean on a LG cooktop?
F3 on an LG cooktop means the control system is getting no feedback signal from the front left cooking zone. The cooktop monitors each induction zone through its own module, and when that communication is lost, F3 is displayed to alert you that the front left zone cannot operate safely. The cooktop will disable that zone until the fault is corrected.
Can I fix the F3 error myself, or do I need a technician?
If you are comfortable working with appliance electronics, you can begin by checking the CN01 connector on the front IH module for a loose or unseated connection, which sometimes resolves the issue without any parts. Beyond that initial check, diagnosing a failed wiring harness or replacing an IH module or control board requires disassembly and basic electrical knowledge. If you are not confident working inside the cooktop, a qualified technician is the safer choice.
Is it safe to keep using the cooktop with an F3 error?
The front left cooking zone will be disabled while the F3 error is active, so you cannot use that specific burner. The remaining cooking zones may continue to function, but you should address the fault promptly to avoid any secondary damage to the control board or wiring from an unresolved module fault. Do not attempt to bypass the error code to force the front left zone to operate.
Will resetting the cooktop clear the F3 error?
Powering the cooktop off at the circuit breaker for a few minutes and then restoring power will clear the displayed error temporarily, but if the underlying connection or component fault is still present, F3 will return as soon as the control system checks the front left zone again. A reset is useful for confirming whether the fault is intermittent, but it is not a repair.
How much does it cost to repair an F3 error on an LG cooktop?
Repair costs vary depending on the root cause. If the fix is simply reseating the CN01 connector, you may only pay for a service call, typically in the range of $75 to $150. Replacing a front IH module or wiring harness generally adds $100 to $300 or more in parts, while a main control board replacement can bring the total repair cost to $200 to $500 or higher depending on your region and the technician's labor rate.

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