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Error code reference

LG Refrigerator Error Code RT sensor

Room temperature sensor abnormal

LG codesLG refrigerator codes

Room temperature sensor abnormal - short circuit or open circuit in the ambient room temperature sensor.

First step from the service manual

Check for loose connection at CON5, then unplug connector and measure resistance between white wires.

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

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What RT sensor means on a LG refrigerator

The RT sensor error on an LG refrigerator indicates an abnormal signal from the ambient room temperature sensor, also called the room temperature or environmental sensor. This sensor monitors the temperature of the surrounding air outside the refrigerator cabinet, and the control board uses that data to adjust compressor cycles, fan speeds, and cooling efficiency based on ambient conditions. When the control board detects a short circuit or open circuit in this sensor circuit, it logs the RT sensor fault and may limit or alter normal operation.

The sensor itself is a negative temperature coefficient (NTC) thermistor, meaning its electrical resistance decreases as temperature rises. The control board reads the resistance value across the sensor to calculate the ambient temperature. A short circuit condition produces a resistance reading near zero ohms, while an open circuit produces an infinite or out-of-range resistance reading. Both conditions fall outside the sensor's normal operating resistance window and trigger the fault code.

Diagnosis begins at connector CON5, which carries the sensor circuit wiring. The first step is inspecting CON5 for any loose, corroded, or damaged pins. If the connection appears sound, unplug the connector and measure resistance directly between the white wires of the sensor circuit using a multimeter. A reading that is near zero ohms points to a short circuit, while a reading of infinite resistance (OL) confirms an open circuit. Either result typically indicates a failed sensor or damaged wiring between the sensor and the connector.

Source: manufacturer service documentation.

Common causes of RT sensor

  1. 01

    Failed RT sensor (thermistor)

    Part replacement

    The NTC thermistor itself has failed internally, resulting in either a short circuit or open circuit reading. This is the most common cause and is confirmed when resistance measured directly at the sensor terminals reads near zero ohms or shows no continuity at all.

  2. 02

    Loose or disconnected connector at CON5

    Wiring / connection

    The sensor wiring connector at CON5 may have vibrated loose or become partially unseated, interrupting the circuit. Inspecting and firmly reseating the connector is the first recommended diagnostic step before any component replacement.

  3. 03

    Damaged or broken sensor wiring

    Part replacement

    The white sensor wires running between the sensor and CON5 may be pinched, chafed, or broken, causing an open or short circuit in the harness rather than in the sensor itself. A visual inspection of the wiring path and a continuity test of the individual wires can isolate this condition.

  4. 04

    Corroded connector pins at CON5

    Wiring / connection

    Moisture or age can cause oxidation on the terminals inside CON5, increasing resistance or breaking the circuit entirely. Corroded pins may appear discolored or pitted and will often cause intermittent faults before becoming a persistent error.

  5. 05

    Control board fault

    Part replacement

    In rare cases the main control board may misinterpret or fail to read the sensor circuit correctly even when the sensor and wiring are intact. This is typically a diagnosis of exclusion, confirmed only after the sensor and wiring harness have been tested and found to be within normal specifications.

See the test procedure for each cause

Frequently asked questions about RT sensor

What does RT sensor mean on a LG refrigerator?
The RT sensor error means the control board has detected an abnormal condition in the ambient room temperature sensor circuit, specifically a short circuit or open circuit. This sensor is a thermistor that measures the temperature of the air surrounding the refrigerator so the control board can optimize cooling performance. When the sensor circuit fails, the board can no longer receive a valid temperature reading from it. The error code alerts you that the sensor or its wiring needs to be inspected and tested.
Can I fix the RT sensor error myself?
A knowledgeable DIYer can perform the initial diagnostic steps, which include checking the connector at CON5 for a loose connection and measuring resistance across the white sensor wires with a multimeter. If the connector simply needs to be reseated, no parts are required. Replacing a failed thermistor sensor is also a manageable repair for someone comfortable working with appliance wiring, though it does require sourcing the correct replacement sensor for your specific LG model.
Is it safe to keep using my refrigerator while the RT sensor error is showing?
The refrigerator may continue to run with this error active, but without accurate ambient temperature data the control board cannot optimize its cooling cycles properly. This could lead to reduced efficiency or inconsistent temperature performance over time. It is best to address the fault promptly to avoid potential food safety issues caused by improper cooling.
How much does it cost to repair an RT sensor error on an LG refrigerator?
If the fix is simply reseating a loose connector at CON5, there may be no parts cost at all, though a service call fee from a technician would still apply if you hire one. Replacing a faulty room temperature thermistor sensor typically costs between $20 and $75 for the part alone, depending on the model. With professional labor, the total repair cost generally falls in the range of $100 to $250.
Will resetting my LG refrigerator clear the RT sensor error?
Performing a power reset by unplugging the refrigerator for a few minutes may temporarily clear the error code, but the fault will return if the underlying problem with the sensor or wiring has not been corrected. A reset should not be used as a substitute for proper diagnosis. The error will persist or reappear until the short circuit or open circuit condition in the RT sensor circuit is actually repaired.

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