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Error code reference

LG Refrigerator Error Code F-sensor open/short

Freezer room temperature sensor has an open or short circuit fault, detected when sensor reading is below…

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Freezer room temperature sensor has an open or short circuit fault, detected when sensor reading is below -50°C or above +50°C.

First step from the service manual

Check F-sensor resistance and wiring; replace sensor if faulty.

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
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What F-sensor open/short means on a LG refrigerator

The F-sensor open/short error on an LG refrigerator indicates a fault in the freezer room temperature sensor circuit. The control board continuously monitors the electrical signal from this thermistor-type sensor, and it triggers this fault code when the sensor reading falls below -50°C or rises above +50°C. These extreme readings tell the board that the sensor is either completely disconnected (open circuit) or has a short to ground or another conductor (short circuit), rather than returning a valid resistance value within the normal operating range.

The freezer temperature sensor is a negative temperature coefficient (NTC) thermistor, meaning its resistance decreases as temperature rises. Under normal freezer conditions, the sensor should output a resistance value that the control board can interpret as a real temperature. When the wiring harness is broken, a connector is corroded or loose, or the sensor itself has failed internally, the board receives a signal that falls outside its acceptable window. An open circuit typically sends resistance toward infinity, while a short circuit pulls it toward zero, both of which map to temperatures outside the -50°C to +50°C threshold.

Common triggers include physical damage to the sensor wire harness from ice buildup, rodent damage, or repeated contact with freezer components during door operation. Connector pins in the wiring harness can also corrode over time, especially in humid environments. In some cases, a heavy frost or ice accumulation around the sensor can cause a short. The first diagnostic step is to measure the sensor resistance at the connector and inspect the full wiring run back to the control board before replacing any components.

Source: manufacturer service documentation.

Common causes of F-sensor open/short

  1. 01

    Failed freezer temperature sensor

    Part replacement

    The NTC thermistor sensor itself has failed internally, causing it to read outside the valid range. Measure resistance at the sensor terminals; a reading of zero or infinite ohms with the wiring intact confirms a bad sensor.

  2. 02

    Damaged or broken wiring harness

    Part replacement

    The wire running from the freezer sensor to the control board can be pinched, cut, or broken by ice buildup, freezer baskets, or repeated flexing near the door. Inspect the full wire run for visible breaks or kinks.

  3. 03

    Loose or corroded connector

    Wiring / connection

    The connector joining the sensor to the wiring harness can become loose or develop corrosion on its pins, creating an intermittent or permanent open circuit. Unplug and reseat the connector, then check for green or white oxidation on the terminals.

  4. 04

    Ice accumulation shorting or dislodging the sensor

    Wiring / connection

    Excessive frost or ice buildup in the freezer compartment can physically dislodge the sensor from its mounting clip or cause moisture to short the circuit. Defrost the freezer completely and recheck sensor placement and readings.

  5. 05

    Faulty control board

    Part replacement

    If the sensor and all wiring test within normal resistance values but the error persists, the control board's sensor input circuit may have failed. This is the least common cause and should only be considered after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about F-sensor open/short

What does F-sensor open/short mean on a LG refrigerator?
This error code indicates that the freezer room temperature sensor has an open or short circuit fault. The control board detected a sensor reading below -50°C or above +50°C, which falls outside any real operating condition and signals an electrical failure in the sensor or its wiring. The freezer may not maintain proper temperature while this fault is active, so the issue should be addressed promptly.
Can I fix the F-sensor error myself?
Many homeowners and DIYers can handle this repair with basic electrical knowledge and a multimeter. The process involves unplugging the refrigerator, locating the freezer temperature sensor, checking the connector and wiring for damage, and measuring sensor resistance to determine if the sensor or wiring is at fault. Replacing an NTC thermistor sensor is a straightforward part swap, but if the control board is involved, professional service is recommended.
Is it safe to keep using my LG refrigerator with this error?
Continuing to run the refrigerator with an active F-sensor fault is not recommended for extended periods. Without accurate freezer temperature feedback, the compressor and cooling system may operate incorrectly, leading to food spoilage or potential overworking of components. Use the freezer only as a temporary measure while arranging the repair.
How much does it cost to fix the F-sensor error on an LG refrigerator?
If only the freezer temperature sensor needs replacement, parts typically range from $15 to $50 depending on the model, and the repair is relatively inexpensive. If a wiring harness repair or connector replacement is needed, costs remain in a similar range. A control board replacement is the most expensive scenario, with parts costs ranging from $100 to $300 or more, plus labor if a technician is hired.
Will resetting my LG refrigerator clear the F-sensor error code?
A reset, such as unplugging the refrigerator for a few minutes, may temporarily clear the fault code from the display. However, if the underlying sensor, wiring, or connector fault still exists, the error will return once the control board performs its next sensor check. A permanent fix requires diagnosing and repairing the actual electrical fault in the sensor circuit.

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