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Error code reference

LG Range Error Code F1

Key pad held down too long or shorted key

LG codesLG range codes

Key pad held down too long or shorted key — a key pad is continuously short for more than 60 seconds.

First step from the service manual

Unplug range, remove keypad tail connector, plug back in and check if F-1 recurs; if so, inspect main PCB connector CN11 for pin-to-pin short.

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

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What F1 means on a LG range

The F1 error code on an LG range indicates that one or more keys on the control keypad has been detected in a continuously active (shorted) state for more than 60 seconds. The control board monitors keypad input signals and expects each key to return to an open state after being pressed. When a key remains electrically closed beyond the 60-second threshold, the main PCB interprets this as a fault condition and triggers the F1 code to prevent unintended operation of the appliance.

The keypad communicates with the main PCB through a ribbon-style tail connector, typically routed to a dedicated connector on the board labeled CN11. A short can originate at several points along this signal path: within the keypad membrane itself (where conductive layers make unwanted contact), along the ribbon cable (due to a pinch, fold, or moisture intrusion), at the tail connector interface, or directly at the PCB connector pins. A pin-to-pin short at CN11 means two adjacent signal lines are making electrical contact, causing the board to read a key as perpetually pressed.

Diagnosing F1 begins by disconnecting the keypad tail connector from the main PCB and powering the range back on. If the F1 code disappears with the keypad disconnected, the fault lies in the keypad assembly or its cable. If F1 persists after disconnecting the keypad, attention shifts to connector CN11 on the main PCB, where a solder bridge, bent pin, or debris-caused short may be responsible. Moisture or food contamination introduced through the control panel surface is a frequent contributing factor in keypad membrane failures.

Source: manufacturer service documentation.

Common causes of F1

  1. 01

    Failed keypad membrane

    Part replacement

    The conductive layers inside the membrane keypad can degrade, warp, or stick together, causing one or more key positions to read as continuously pressed. This is the most common source of F1 and is confirmed when the error clears after unplugging the keypad tail connector.

  2. 02

    Moisture or contamination under the keypad

    Wiring / connection

    Liquids or food debris seeping beneath the control panel surface can bridge the conductive contacts of the keypad membrane, simulating a held key. Inspect the keypad surface and interior for visible residue or corrosion.

  3. 03

    Damaged or pinched ribbon cable

    Part replacement

    The flexible ribbon cable connecting the keypad to the main PCB can develop an internal short if it is bent sharply, pinched during a previous repair, or worn at the connector insertion point. Visually inspect the full length of the cable for creases or damage.

  4. 04

    Pin-to-pin short at PCB connector CN11

    Wiring / connection

    Adjacent pins at the CN11 connector on the main PCB can short due to a solder bridge, bent pin, or conductive debris. This is indicated when F1 continues to appear even after the keypad tail connector has been fully removed.

  5. 05

    Faulty main PCB

    Part replacement

    If cleaning CN11 and replacing the keypad assembly do not resolve the fault, the main PCB itself may have an internal failure in the key input detection circuit. Board replacement is the corrective action in this scenario.

See the test procedure for each cause

Frequently asked questions about F1

What does F1 mean on a LG range?
F1 on an LG range means the control board has detected a key on the keypad that appears to have been held down or shorted continuously for more than 60 seconds. The range flags this as a fault to prevent unintended cooking functions from activating. The source of the problem is typically in the keypad membrane, the ribbon cable, or the CN11 connector on the main PCB.
Will unplugging the range reset the F1 error code?
Unplugging the range will clear the active display of the F1 code, but the error will return as soon as the faulty component is detected again on power-up. A reset is useful as a first diagnostic step to confirm the fault is real and repeatable, but it does not fix the underlying short in the keypad or control board circuit.
How do I fix the F1 error on my LG range?
Start by unplugging the range and disconnecting the keypad tail connector from the main PCB at connector CN11, then restore power. If the F1 code does not return, the keypad assembly or its ribbon cable is the source and will need to be inspected or replaced. If F1 persists with the keypad disconnected, inspect CN11 on the main PCB for bent pins, solder bridges, or debris causing a pin-to-pin short, and clean or repair as needed.
Is the F1 error on an LG range a safety hazard?
The F1 error is a protective fault code designed to prevent uncontrolled range operation caused by a stuck or shorted key. While the error itself is a safety feature, you should not continue using the range until the fault is resolved, as the underlying short could potentially trigger unintended burner or oven activation. Unplug the appliance until the repair is completed.
How much does it cost to repair an F1 error on an LG range?
Repair costs depend on which component has failed. A replacement keypad or control panel overlay typically costs in the range of $30 to $120 for parts alone. If the main PCB requires replacement, parts costs generally range from $100 to $300 or more depending on the specific model. Adding professional labor will increase the total, so obtaining a diagnostic estimate from a certified technician before committing to a repair is advisable.

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