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Error code reference

LG Refrigerator Error Code F-SENSOR ERROR

Freezer sensor fault

LG codesLG refrigerator codes

Freezer sensor fault — sensor housing slip-out, contact defect, wire cut, wire short, or sensor temperature out of range (above 122°F/+50°C or below -122°F/-50°C).

First step from the service manual

Check voltage between Main PCB CN30 pins 2↔3; it shall be within 4.5V~1.0V.

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

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What F-SENSOR ERROR means on a LG refrigerator

The F-SENSOR ERROR on an LG refrigerator indicates a fault in the freezer temperature sensor circuit. This sensor is a negative temperature coefficient (NTC) thermistor responsible for continuously reporting freezer compartment temperature to the main PCB. When the control board detects a signal outside the expected operating window, specifically a temperature reading above 122°F (+50°C) or below -122°F (-50°C), it flags the error to prevent the compressor and cooling system from operating on bad data. The sensor communicates with the board through a dedicated connector, CN30, and the first diagnostic step is to measure DC voltage between pins 2 and 3 on that connector. A healthy circuit reads between 1.0V and 4.5V depending on ambient freezer temperature.

There are five primary root causes for this fault: the sensor has physically slipped out of its housing or mounting clip, there is a contact defect at the connector itself, the wiring harness has been cut or pinched, the circuit has a short to ground or to another wire, or the sensor element itself has failed and is reading a temperature value outside its valid range. Physical inspection of the sensor housing, wiring harness routing, and connector seating should follow the voltage test. If the voltage at CN30 pins 2 and 3 is outside the 1.0V to 4.5V range, the fault is confirmed in that circuit and further isolation between the sensor, harness, and board is needed to pinpoint the defective component.

Source: manufacturer service documentation.

Common causes of F-SENSOR ERROR

  1. 01

    Sensor slipped out of housing

    Wiring / connection

    The freezer sensor can work loose from its mounting clip or housing, causing it to read ambient air instead of the correct location temperature and produce an out-of-range signal. Visually inspect the sensor mounting point inside the freezer compartment for a dislodged or dangling sensor.

  2. 02

    Connector contact defect at CN30

    Wiring / connection

    Corrosion, bent pins, or a loose connection at the CN30 connector on the main PCB can interrupt the voltage signal between pins 2 and 3. Check that the connector is fully seated and that the terminals are clean and undamaged.

  3. 03

    Wiring harness damage (cut or short)

    Part replacement

    The sensor wiring can be pinched by a shelf bracket, cut during a prior repair, or shorted against another circuit, all of which pull the voltage reading outside the 1.0V to 4.5V valid range. Inspect the full harness run from the sensor to the main PCB for visible damage.

  4. 04

    Failed freezer temperature sensor

    Part replacement

    The NTC thermistor element inside the sensor can fail open or short internally, causing the board to read an impossible temperature value. If wiring and connections test good but voltage at CN30 pins 2 and 3 is still out of range, the sensor itself needs replacement.

  5. 05

    Main PCB fault

    Part replacement

    If the sensor, harness, and connector all test good but the error persists, the main PCB may have a defective input circuit on CN30. This is the least common cause and should only be considered after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about F-SENSOR ERROR

What does F-SENSOR ERROR mean on a LG refrigerator?
The F-SENSOR ERROR indicates a fault in the freezer compartment temperature sensor circuit. The main PCB has detected a sensor reading above 122°F (+50°C) or below -122°F (-50°C), which is outside the valid operating range. The fault can be caused by a loose sensor, a wiring problem, a bad connector, or a failed sensor. Voltage at the main PCB connector CN30 pins 2 and 3 should measure between 1.0V and 4.5V in a properly functioning circuit.
Can I fix the F-SENSOR ERROR myself?
Some causes are DIY-friendly. If the sensor has simply slipped out of its mounting clip, reseating it may clear the error. Inspecting and reseating the CN30 connector on the main PCB is also straightforward. Replacing the freezer sensor itself is a moderate-level repair that most handy homeowners can complete. Wiring harness repairs or main PCB replacement are better handled by a technician.
Is it safe to keep using my refrigerator with an F-SENSOR ERROR?
It is not advisable to continue using the refrigerator normally with this error active. Without a valid freezer temperature reading, the control board cannot regulate cooling accurately, which means freezer temperatures may drift and food safety could be compromised. Addressing the fault promptly is recommended.
How much does it cost to repair the F-SENSOR ERROR on an LG refrigerator?
If the repair is just reseating a loose sensor or connector, there may be no parts cost at all. A replacement freezer temperature sensor typically costs in the range of $15 to $50 for the part. If a wiring harness or the main PCB needs replacement, total repair costs including labor can range from $150 to $400 or more depending on your region and service provider.
Will resetting my LG refrigerator clear the F-SENSOR ERROR?
A power reset may temporarily clear the error code, but if the underlying fault in the sensor, wiring, or connector has not been corrected, the error will return. The code is triggered by an active electrical condition in the sensor circuit, not a software glitch, so a reset alone is not a fix. Proper diagnosis starting with the voltage check at CN30 pins 2 and 3 is required to resolve the error permanently.

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