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Error code reference

LG Microwave Error Code F-2

Shorted or faulty connection at CN3 connector during toaster operation (two wire leads may be shorted…

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Shorted or faulty connection at CN3 connector during toaster operation (two wire leads may be shorted together).

First step from the service manual

Check the CN3 connector whether 2 wire leads are attached/shorted; separate leads as far as possible.

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

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What F-2 means on a LG microwave

The F-2 error code on an LG microwave indicates a shorted or faulty connection at the CN3 connector, and it occurs specifically during toaster operation. The CN3 connector is a multi-wire harness connection point on the control board circuit. When two wire leads within or around this connector make unintended contact with each other, the control system detects an abnormal electrical condition and triggers the F-2 fault to prevent damage to internal components.

The most direct cause of this error is physical contact between two wire leads at the CN3 connector. This can happen if the wiring harness has loosened over time, if insulation on adjacent wires has worn or melted, or if the connector was disturbed during a previous repair or cleaning. The control board reads the shorted signal as an out-of-range condition and halts toaster operation to protect the circuit.

Diagnosing this fault starts with a visual and physical inspection of the CN3 connector. Technicians should check whether the two wire leads are touching, pinched together, or have compromised insulation. If the leads are found to be in contact, they should be carefully separated and re-routed so they cannot touch again. If the wiring or connector housing is damaged, replacement of the harness or connector assembly will be necessary before the appliance can safely return to operation.

Source: manufacturer service documentation.

Common causes of F-2

  1. 01

    Shorted wire leads at CN3 connector

    Wiring / connection

    The two wire leads at the CN3 connector are making direct contact with each other, creating a short circuit. This is the primary cause of the F-2 code and can often be seen visually during inspection.

  2. 02

    Damaged or worn wire insulation

    Part replacement

    Heat exposure during toaster operation can degrade the plastic insulation on wires near the CN3 connector, allowing bare conductors on adjacent leads to contact each other. Look for discoloration, melting, or cracking along the wire lengths near the connector.

  3. 03

    Loose or dislodged wiring harness

    Wiring / connection

    Vibration or a prior repair attempt may have caused the wiring harness to shift, bringing two leads into contact at or near the CN3 connector. Check that the harness is properly seated and secured.

  4. 04

    Faulty CN3 connector housing

    Part replacement

    The connector housing itself may be cracked or deformed, allowing the wire terminals inside to bridge together. Inspect the plastic connector body for physical damage or terminal misalignment.

  5. 05

    Pinched wiring from reassembly

    Wiring / connection

    If the microwave outer cabinet was recently removed and replaced, wires near the CN3 connector could have been pinched between panels, forcing leads into contact. Re-examine the routing path of the wiring harness near that connector.

See the test procedure for each cause

Frequently asked questions about F-2

What does F-2 mean on a LG microwave?
The F-2 code on an LG microwave indicates a shorted or faulty connection at the CN3 connector, and it is triggered during toaster operation. Specifically, it means two wire leads at that connector are in contact with each other when they should be separated. The appliance shuts down the toaster function to prevent electrical damage. Inspecting and separating those wire leads is the first step toward resolving this fault.
Can I fix the F-2 error on my LG microwave myself?
If the cause is simply two wire leads that have shifted and are touching at the CN3 connector, separating them and re-routing the wiring may resolve the issue without replacing any parts. However, if the wires have damaged insulation or the connector housing is broken, those components will need to be replaced. Because microwaves contain high-voltage capacitors that can retain a dangerous charge even when unplugged, internal repairs should only be performed by someone familiar with high-voltage appliance safety procedures.
Is it safe to use my LG microwave when the F-2 error is displayed?
No, you should not attempt to use the appliance while the F-2 fault is active. The error indicates a wiring short in the toaster circuit, which poses a risk of further electrical damage or potentially a fire hazard if the condition is not corrected. Keep the microwave unplugged until the CN3 connector and associated wiring have been inspected and the fault is cleared.
Will resetting my LG microwave clear the F-2 error code?
Simply resetting or power-cycling the microwave is unlikely to permanently clear the F-2 code if the underlying short at the CN3 connector has not been corrected. The fault will typically return as soon as the toaster function is activated again. The wiring issue must be physically resolved before the error will stay cleared.
How much does it cost to repair an F-2 error on an LG microwave?
If the fix only requires separating and re-routing the wire leads at the CN3 connector with no parts needed, a repair technician visit could range from around $75 to $150 for labor depending on your area. If the wiring harness or connector needs to be replaced, parts and labor combined could run between $100 and $250. The overall cost depends on whether additional damage to the wiring or control board is found during inspection.

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