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Error code reference

LG Refrigerator Error Code F-1-ⓐ

Ambient (external) sensor part error

LG codesLG refrigerator codes

Ambient (external) sensor part error - sensor housing separation, contact error, disconnection, or short circuit; detected when temperature reads more than 149°F (+65°C) or less than -58°F (-50°C).

First step from the service manual

Check if MAIN PCB Connector CN31 is inserted correctly; measure resistance at CN31#1 ↔ #4 and compare to temperature table.

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

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What F-1-ⓐ means on a LG refrigerator

The F-1-ⓐ error code on an LG refrigerator indicates a fault with the ambient (external) temperature sensor, also called the room temperature sensor. This sensor monitors the temperature of the air surrounding the refrigerator and feeds that data to the main control board so the unit can adjust its cooling performance based on environmental conditions. The error triggers when the sensor reports a temperature above 149°F (+65°C) or below -58°F (-50°C), values that fall outside any realistic operating range and signal that the sensor or its circuit has failed rather than that the actual ambient temperature is extreme.

The fault can originate from several points in the sensor circuit. Physical separation of the sensor from its housing, poor contact at the connector, a broken wire in the harness, or a short circuit within the sensor itself can all push the reported temperature reading into the out-of-range zone that triggers this code. The main PCB connector involved is CN31, and the diagnostic process begins there. A technician should verify that CN31 is fully seated, then measure resistance across pins CN31#1 and CN31#4 and compare those readings against the temperature-resistance table for this sensor. A properly functioning NTC-type ambient sensor will show a predictable resistance value corresponding to the actual room temperature.

If the resistance reading at CN31 is open (infinite resistance) or near zero ohms, the sensor or wiring harness is the likely culprit. If connector seating and wiring check out but the resistance is still out of spec, the sensor itself needs replacement. In cases where the connector and sensor both measure correctly, attention shifts to the main PCB, which may be misreading the signal due to a board-level fault.

Source: manufacturer service documentation.

Common causes of F-1-ⓐ

  1. 01

    Loose or improperly seated CN31 connector

    Wiring / connection

    The connector at CN31 on the main PCB can work loose over time due to vibration. A partially seated connector causes intermittent or complete loss of signal, which pushes the reading out of range and triggers the fault.

  2. 02

    Failed or out-of-range ambient temperature sensor

    Part replacement

    The sensor itself can fail internally, resulting in a resistance value that corresponds to a temperature above 149°F or below -58°F. Measuring resistance across CN31#1 and #4 and comparing to the temperature table will confirm this.

  3. 03

    Damaged or broken sensor wiring harness

    Part replacement

    A wire in the harness connecting the ambient sensor to CN31 can break, fray, or short against a metal surface. Visually inspect the harness for pinch points, cuts, or areas where insulation has worn through.

  4. 04

    Sensor housing separation

    Wiring / connection

    The sensor can physically separate from its mounting housing, exposing it to inaccurate temperature readings or causing the connector contacts to lose their grip. Check that the sensor is fully secured in its bracket and that no physical damage is visible.

  5. 05

    Main PCB fault

    Part replacement

    If the sensor, harness, and CN31 connector all test within specification, the main control board may be the source of the error due to a failure in the input circuit that reads the sensor signal.

See the test procedure for each cause

Frequently asked questions about F-1-ⓐ

What does F-1-ⓐ mean on a LG refrigerator?
The F-1-ⓐ code means the refrigerator has detected a problem with the ambient temperature sensor, the sensor that monitors the air temperature around the outside of the unit. The error activates when the sensor reports a temperature above 149°F (65°C) or below -58°F (-50°C), both of which indicate a sensor or wiring fault rather than an actual temperature extreme. Common causes include a loose connector at the main board, a broken wire, or a failed sensor.
Can I fix the F-1-ⓐ error on my LG refrigerator myself?
Some steps are DIY-friendly, particularly checking whether the connector at CN31 on the main PCB is fully seated, since a loose connector is among the most common causes. If that does not resolve it, testing sensor resistance requires a multimeter and the ability to interpret a resistance-to-temperature table. Replacing the sensor or wiring harness is within reach for experienced DIYers, but main PCB replacement is generally best handled by a qualified technician.
Will resetting my LG refrigerator clear the F-1-ⓐ error code?
A reset may temporarily clear the code, but if the underlying fault in the sensor, wiring, or connector is not corrected, the error will return once the control board re-evaluates the sensor signal. Resetting without fixing the root cause does not restore reliable operation and can mask a problem that affects cooling performance.
Is it safe to keep using my LG refrigerator while the F-1-ⓐ code is active?
The refrigerator may continue to run while this code is active, but without accurate ambient temperature data the control board cannot optimize cooling performance correctly. Food safety could be affected if the unit begins to underperform. It is best to diagnose and correct the fault promptly rather than rely on the appliance to maintain safe temperatures indefinitely.
How much does it cost to repair an F-1-ⓐ error on an LG refrigerator?
Repair costs depend on the root cause. A replacement ambient temperature sensor typically runs in the range of $15 to $50 for the part alone. A new wiring harness can range from $20 to $80 depending on the model. If the main PCB is at fault, board replacement can cost anywhere from $100 to $300 or more for the part, with additional labor costs if a technician is involved.

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