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Error code reference

LG Refrigerator Error Code R-13

R-DEF-Sensor (Fridge Defrost Sensor) Error

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R-DEF-Sensor (Fridge Defrost Sensor) Error - sensor housing slipped out, defective wire contact, wire cut, wire short, or sensor pickup temp is over 149°F (65°C) or under -58°F (-50°C).

First step from the service manual

Check voltage between MAIN PCB CN30 #8 and #1; should 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 R-13 means on a LG refrigerator

The R-13 error code on an LG refrigerator indicates a fault in the refrigerator compartment defrost sensor, also called the R-DEF sensor. This sensor monitors temperatures during the defrost cycle to prevent the evaporator from overheating and to confirm that defrost is progressing correctly. When the control board detects a sensor reading outside the valid operating range, specifically above 149°F (65°C) or below -58°F (-50°C), or when it detects an open or shorted circuit in the sensor wiring, it triggers the R-13 fault and halts normal operation to protect the system.

The first diagnostic step is to check the voltage between pins 8 and 1 on connector CN30 at the main PCB. A healthy sensor circuit will produce a voltage reading within the range of 1.0V to 4.5V. A reading outside this range points to either a wiring problem or a failed sensor. Readings near 0V or at the supply rail voltage typically indicate a short or open circuit in the sensor wiring harness rather than a failed sensor element itself.

Physical causes of this code include the sensor housing slipping out of its mounting bracket on the evaporator, which causes the sensor to read incorrect temperatures due to poor thermal contact. Damaged wiring is also common, particularly at points where the harness flexes near the evaporator cover or passes through grommets. A defective sensor element that has drifted out of calibration will also trigger this fault even when the wiring and connections appear intact.

Source: manufacturer service documentation.

Common causes of R-13

  1. 01

    Sensor housing displaced from mounting position

    Wiring / connection

    The defrost sensor housing can slip out of its bracket on the evaporator, causing inaccurate temperature readings. Inspect the sensor physically to confirm it is seated correctly in its mounting clip against the evaporator coil.

  2. 02

    Damaged or broken wiring harness

    Part replacement

    Wiring to the R-DEF sensor can be cut, pinched, or broken, especially at points where the harness routes around the evaporator cover or through the cabinet wall. Visually trace the full length of the wiring and check for visible damage or corrosion at connector pins.

  3. 03

    Defective wire contact at connector

    Wiring / connection

    Loose or corroded pin contacts at the CN30 connector on the main PCB can cause intermittent or out-of-range voltage readings. Check the connector for bent pins, corrosion, or a poor seat, and measure voltage between CN30 pin 8 and pin 1 to confirm signal integrity.

  4. 04

    Shorted sensor wiring

    Part replacement

    A short circuit in the sensor harness will drive the voltage reading outside the valid 1.0V to 4.5V window, triggering the R-13 fault. Inspect the harness for areas where insulation has worn through and wires may be contacting each other or a metal surface.

  5. 05

    Failed defrost sensor element

    Part replacement

    The sensor itself can fail internally, producing readings outside the valid temperature range of -58°F to 149°F even when wiring and connections are intact. If voltage and wiring checks are normal, replace the R-DEF sensor.

See the test procedure for each cause

Frequently asked questions about R-13

What does R-13 mean on a LG refrigerator?
The R-13 code indicates an error with the refrigerator compartment defrost sensor (R-DEF sensor). The control board has detected either a wiring fault such as a cut, short, or loose connection, or a sensor temperature reading outside the valid range of -58°F to 149°F. The first diagnostic step is checking the voltage at connector CN30 on the main PCB, which should measure between 1.0V and 4.5V on a healthy circuit.
Can I fix the R-13 error myself, or do I need a technician?
Some causes of the R-13 error are accessible to a knowledgeable DIYer. Reseating a displaced sensor housing or reconnecting a loose wire connector does not require specialized tools. However, diagnosing a shorted harness or replacing the main PCB connector requires a multimeter and comfort working around refrigerator electrical components, so a technician may be appropriate if you are not confident with that process.
Is it safe to keep using my refrigerator while the R-13 code is active?
A faulty defrost sensor means the refrigerator may not complete its defrost cycles correctly. Over time this can cause ice buildup on the evaporator coil, which reduces cooling performance and can lead to food spoilage. It is best to address the fault promptly rather than continue operating the refrigerator with this code active.
How much does it cost to repair the R-13 error on an LG refrigerator?
Repair costs vary depending on what is causing the fault. A replacement defrost sensor part typically costs in the range of $20 to $60. If a wiring harness needs to be replaced, parts and labor combined can range from $100 to $250. A main PCB replacement, if the connector or board is damaged, can bring total costs to $200 to $400 or more depending on the specific model.
Will resetting the refrigerator clear the R-13 error code?
A power reset may temporarily clear the R-13 code, but the error will return if the underlying fault is not corrected. If the sensor is displaced, the wiring is damaged, or the sensor element has failed, the control board will detect the problem again once normal operation resumes. A reset should only be used as part of the diagnostic process, not as a permanent solution.

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