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Error code reference

LG Refrigerator Error Code F-area defroster sensor open/short

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

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Freezer evaporator defrost 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-defrost 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-area defroster sensor open/short means on a LG refrigerator

The F-area defroster sensor open/short error on an LG refrigerator indicates a fault in the freezer evaporator defrost sensor circuit. This sensor, also called the F-defrost sensor, monitors the temperature of the freezer evaporator coil during and after defrost cycles. The control board continuously reads the sensor's resistance output and converts it to a temperature value. When that reading falls below -50°C or rises above +50°C, the board interprets the signal as out-of-range and flags an open or short circuit condition, respectively.

An open circuit occurs when the sensor's internal thermistor element breaks or a wiring connection is severed, causing resistance to read as infinite. A short circuit occurs when the sensor leads contact each other or a grounded surface, driving resistance toward zero. Both conditions push the calculated temperature reading to an extreme that falls outside the sensor's valid operating window, triggering the fault code. The sensor itself is a Negative Temperature Coefficient thermistor, meaning its resistance decreases as temperature increases.

Common causes include a failed sensor thermistor, damaged wiring harness connectors near the evaporator (which is a cold and humid environment prone to corrosion and brittleness), or a loose connector at either the sensor end or the control board. In some cases, ice buildup around the sensor can physically stress the wiring leads and cause an intermittent open. Diagnosing this fault requires checking sensor resistance with a multimeter and inspecting the full wiring path from the sensor to the main control board.

Source: manufacturer service documentation.

Common causes of F-area defroster sensor open/short

  1. 01

    Failed defrost sensor thermistor

    Part replacement

    The NTC thermistor inside the F-defrost sensor can fail internally, causing an open or short circuit. This is the most common cause and is confirmed by measuring sensor resistance with a multimeter and comparing to expected values for a given temperature.

  2. 02

    Corroded or damaged wiring harness connector

    Wiring / connection

    The connector at the sensor or at the control board can corrode or develop a poor connection in the freezer's cold, humid environment. Inspect both connector ends for corrosion, bent pins, or moisture intrusion.

  3. 03

    Broken or pinched sensor wiring

    Wiring / connection

    The wiring between the defrost sensor and the control board can become brittle, pinched during a prior repair, or damaged by ice formation around the evaporator. A visual inspection of the full wire run and a continuity test will confirm this.

  4. 04

    Ice buildup stressing sensor leads

    Part replacement

    Excessive ice accumulation around the evaporator coil can physically stress or crack the sensor's lead wires, creating an intermittent or permanent open circuit. This is often a secondary symptom of a prior defrost system issue.

  5. 05

    Faulty main control board

    Part replacement

    If the sensor and wiring both test within normal resistance ranges, the control board's sensor input circuit may have failed. This is the least likely cause and should only be considered after ruling out the sensor and wiring.

See the test procedure for each cause

Frequently asked questions about F-area defroster sensor open/short

What does F-area defroster sensor open/short mean on a LG refrigerator?
This error means the control board has detected that the freezer evaporator defrost sensor is reading a temperature below -50°C or above +50°C, which indicates an open or short circuit in the sensor or its wiring. An open circuit typically means a broken thermistor or severed wire, while a short circuit means the sensor leads are contacting each other or a ground. The refrigerator flags this fault to alert you that the defrost cycle monitoring system cannot function correctly.
Can I fix the F-area defroster sensor error myself?
A knowledgeable DIYer can diagnose this fault by testing the defrost sensor's resistance with a multimeter and inspecting the wiring harness for damage or corrosion. If the sensor tests out of range, replacing it is a straightforward repair that involves accessing the freezer evaporator panel. However, if the wiring or control board is involved, the repair becomes more involved and may benefit from professional service.
Is it safe to keep using my LG refrigerator while this error is active?
With this error active, the defrost cycle may not operate correctly, which can lead to ice buildup on the evaporator coil and reduced cooling performance over time. Food safety can be compromised if cooling is significantly impaired. It is best to address the fault promptly rather than continuing to run the refrigerator with a known defrost sensor fault.
Will resetting my LG refrigerator clear the F-area defroster sensor error?
A power reset may temporarily clear the error code from the display, but the fault will return if the underlying sensor or wiring problem is not repaired. The control board re-evaluates the sensor reading continuously, so if the sensor or circuit is still faulty, the code will reappear. A reset alone is not a fix and should only be used as a step during diagnosis.
How much does it cost to repair the F-area defroster sensor fault on an LG refrigerator?
If only the defrost sensor needs replacement, parts typically range from around $15 to $50 depending on the model, making it one of the lower-cost refrigerator repairs. If a service technician is needed, labor costs can bring the total to somewhere in the $100 to $250 range. If the main control board is at fault, parts alone can range from $100 to $300 or more, with labor added on top.

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