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Error code reference

LG Refrigerator Error Code Freezer Room Sensor Error

Sensor system in FZ compartment has errors.

LG codesLG refrigerator codes

Sensor system in FZ compartment has errors.

First step from the service manual

Check voltage of MAIN PCB CN30#3 <-> CN76#1: shall be between 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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  • Wiring diagram references and connector pinouts from the OEM service manual
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What Freezer Room Sensor Error means on a LG refrigerator

The Freezer Room Sensor Error indicates a fault within the temperature sensor circuit located in the freezer compartment of the LG refrigerator. This sensor, commonly referred to as the freezer evaporator or compartment thermistor, reports real-time temperature data to the main PCB so the control board can regulate compressor cycles, fan operation, and defrost timing. When the control board detects a signal outside the expected parameters, it flags this error to alert the technician that the sensor circuit requires inspection.

The primary diagnostic step involves checking the voltage at the main PCB connector CN30 pin 3 relative to CN76 pin 1. Under normal operating conditions, this voltage should read between 1.0V and 4.5V, which corresponds to the thermistor's resistance changing with temperature. A reading outside this range, whether too high or too low, points to either a failed thermistor, a wiring harness fault, or a problem with the main PCB itself. A voltage near 0V or at the supply rail typically indicates a short circuit or open circuit in the sensor loop, respectively.

Thermistors used in freezer compartments are NTC (negative temperature coefficient) type components, meaning their resistance decreases as temperature rises. A failed thermistor that reads infinite resistance or zero resistance will push the voltage signal outside the 1.0V to 4.5V window and trigger the error. Connector corrosion, broken wires in the harness running through the freezer door or cabinet wall, and in rarer cases a faulty main PCB, are also potential sources of this fault.

Source: manufacturer service documentation.

Common causes of Freezer Room Sensor Error

  1. 01

    Failed Freezer Compartment Thermistor

    Part replacement

    The NTC thermistor itself has failed due to age or moisture exposure, producing a resistance value that drives the voltage at CN30 pin 3 outside the 1.0V to 4.5V range. Replacing the thermistor is the most frequent repair for this error.

  2. 02

    Open or Damaged Wiring Harness

    Part replacement

    The wiring running from the freezer sensor to the main PCB can crack or break, especially at flex points near the door hinge or cabinet wall. An open circuit will cause the voltage to read at or near the supply rail maximum, outside the acceptable window.

  3. 03

    Corroded or Loose Connector Pins

    Wiring / connection

    Moisture inside the freezer compartment can cause corrosion at connector CN30 or CN76 on the main PCB. Inspect the pins for green or white oxidation and clean or reseat the connector before condemning other components.

  4. 04

    Short Circuit in Sensor Circuit

    Part replacement

    A pinched or chafed wire in the harness can create a short circuit that pulls the sensor voltage close to 0V, well below the 1.0V minimum. Carefully trace the full length of the sensor harness to locate any damaged insulation.

  5. 05

    Faulty Main PCB

    Part replacement

    If the wiring, connectors, and thermistor all test within spec but the voltage at CN30 pin 3 relative to CN76 pin 1 remains out of range, the main PCB may be failing to supply or read the reference voltage correctly. Board replacement is the last-resort repair after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about Freezer Room Sensor Error

What does Freezer Room Sensor Error mean on a LG refrigerator?
This error indicates that the control board has detected a problem with the temperature sensor circuit in the freezer compartment. The sensor signal voltage at the main PCB should fall between 1.0V and 4.5V during normal operation, and any reading outside that range triggers the fault. The issue can stem from a defective thermistor, damaged wiring, or a connector problem. Until the sensor circuit is repaired, the refrigerator may not regulate freezer temperatures correctly.
Can I fix the Freezer Room Sensor Error myself?
A knowledgeable DIYer comfortable with basic electrical testing can check the wiring harness and connectors for visible damage or corrosion without specialized tools. Measuring voltage at main PCB connectors CN30 pin 3 and CN76 pin 1 requires a multimeter. If the thermistor itself needs replacement, the part is typically accessible inside the freezer compartment, but working with main PCB connectors requires care to avoid further damage.
Is my food safe while the Freezer Room Sensor Error is active?
If the freezer is still running and feels cold, food may remain safe in the short term, but you cannot rely on the appliance to maintain proper freezing temperatures without an accurate sensor signal. The control board cannot make correct decisions about compressor and fan operation without good temperature data. Check that the freezer feels adequately cold and monitor closely, but arrange for repair as soon as possible to avoid food spoilage.
How much does it cost to repair a Freezer Room Sensor Error on an LG refrigerator?
If only the thermistor needs replacement, parts typically cost in the range of $15 to $50, and a technician visit would add labor costs on top of that. If the main PCB is the source of the fault, board replacement can range from $100 to $300 or more for the part alone, plus labor. Getting a professional diagnosis first helps avoid replacing components unnecessarily.
Will resetting my LG refrigerator clear the Freezer Room Sensor Error?
A reset may temporarily clear the error code from the display, but the fault will return if the underlying problem in the sensor circuit has not been corrected. Resetting is useful to confirm whether the error was a transient glitch, such as a briefly loose connector, but it is not a repair. If the code returns after a reset, a proper electrical diagnosis of the sensor wiring and thermistor is required.

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