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Error code reference

LG Refrigerator Error Code C/R-DEF-SEN

C/R defrost sensor failure detected by self-diagnosis.

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C/R defrost sensor failure detected by self-diagnosis.

First step from the service manual

Check resistance at CN30 No.13 ↔ No.14; 0Ω indicates short failure, ∞Ω indicates open failure.

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

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What C/R-DEF-SEN means on a LG refrigerator

The C/R-DEF-SEN error code indicates that the LG refrigerator's self-diagnosis system has detected a failure in the compartment or refrigerator defrost sensor. This sensor is a thermistor responsible for monitoring temperatures during the defrost cycle, allowing the control board to determine when the evaporator has reached the correct temperature and the defrost heater should shut off. When the sensor fails, the refrigerator cannot properly regulate defrost timing, which can lead to frost accumulation on the evaporator coil, reduced cooling performance, or continuous heater operation.

The diagnostic procedure begins at connector CN30, measuring resistance between pins No.13 and No.14. A reading of 0 ohms at these terminals indicates a short circuit failure in the sensor circuit, meaning the sensor or its wiring has an unintended direct connection. A reading of infinite ohms (open circuit) indicates the circuit has been broken, either from a failed sensor, a severed wire, or a disconnected connector. Both conditions render the sensor unable to provide accurate temperature data to the control board.

Common causes include physical damage to the sensor from ice buildup pressing against the component, heat stress from repeated defrost cycles degrading the thermistor element, corroded or loose connector pins at CN30, or wiring harness damage from pinching or abrasion. Confirming which failure type is present, short or open, at CN30 before replacing components helps avoid unnecessary part replacement and correctly identifies whether the fault lies in the sensor itself or the wiring leading to it.

Source: manufacturer service documentation.

Common causes of C/R-DEF-SEN

  1. 01

    Failed defrost sensor thermistor

    Part replacement

    The thermistor element inside the sensor degrades over time due to repeated heating and cooling cycles, causing it to read either open or short circuit. Resistance measured at CN30 pins No.13 and No.14 will be either 0 ohms or infinite ohms, neither of which is within normal operating range.

  2. 02

    Damaged or broken wiring harness

    Part replacement

    The wiring between the defrost sensor and connector CN30 can become pinched, abraded, or cracked, especially if ice buildup has pressed against the harness. Visually inspect the wire run from the evaporator area to CN30 for any visible breaks, burns, or pinch points.

  3. 03

    Corroded or loose connector pins at CN30

    Wiring / connection

    Moisture in the evaporator compartment can cause corrosion at the CN30 connector terminals on pins No.13 and No.14, increasing resistance or breaking the circuit entirely. Unplug the connector and inspect the pins for green or white oxidation and ensure the connector seats firmly.

  4. 04

    Ice accumulation pressing on the sensor

    Wiring / connection

    Excessive frost buildup around the evaporator can physically displace or compress the sensor, damaging its internal element or its wire leads. If a heavy frost accumulation is present, performing a manual defrost and inspecting the sensor afterward can help determine whether ice caused the fault.

  5. 05

    Faulty main control board

    Part replacement

    If the sensor and all associated wiring test within normal parameters, the control board's sensor input circuit may be the source of the false reading. This is the least common cause and should only be considered after the sensor and wiring have been confirmed good.

See the test procedure for each cause

Frequently asked questions about C/R-DEF-SEN

What does C/R-DEF-SEN mean on a LG refrigerator?
C/R-DEF-SEN indicates that the LG refrigerator's self-diagnosis system has detected a failure in the compartment defrost sensor. This sensor is a thermistor that monitors evaporator temperatures during the defrost cycle. The fault is classified as either a short circuit (0 ohms) or an open circuit (infinite ohms), measured at connector CN30 between pins No.13 and No.14. Without a functioning defrost sensor, the refrigerator cannot properly control its defrost cycle.
Can I fix the C/R-DEF-SEN error myself?
A knowledgeable DIYer can perform initial diagnostics by checking the wiring and connector at CN30 for visible damage, corrosion, or loose pins. However, accurately diagnosing a short versus open failure requires a multimeter to test resistance at CN30 pins No.13 and No.14. If the sensor itself has failed, replacing it involves accessing the evaporator compartment and handling electrical components, which many homeowners prefer to leave to a technician.
Is it safe to keep using my LG refrigerator while the C/R-DEF-SEN code is active?
Operating the refrigerator with an active C/R-DEF-SEN code carries some risk. Without a functional defrost sensor, the defrost cycle cannot be properly controlled, which may lead to frost buildup on the evaporator coil, reduced cooling efficiency, or in a short-circuit scenario, a defrost heater that does not shut off at the correct temperature. It is advisable to address the fault promptly to prevent food spoilage or additional component damage.
How much does it cost to repair the C/R-DEF-SEN error on a LG refrigerator?
Repair costs depend on the root cause. If the issue is only a loose or corroded connector, there may be no parts cost, with just a service call fee typically ranging from $75 to $150. A defrost sensor replacement part generally costs between $15 and $50, with total repair costs including labor ranging from $100 to $250. If the control board is at fault, costs can rise to $200 to $400 or more depending on the model.
Will resetting my LG refrigerator clear the C/R-DEF-SEN error code?
A reset may temporarily clear the error code from the display, but it will not resolve the underlying sensor failure. Because the self-diagnosis system actively monitors the defrost sensor circuit, the C/R-DEF-SEN code will return as soon as the control board performs its next diagnostic check and again detects the open or short circuit condition. The sensor or wiring fault must be identified and corrected for the error to clear permanently.

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