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Error code reference

LG Refrigerator Error Code Er rt

Abnormal Room Temperature Sensor

LG codesLG refrigerator codes

Abnormal Room Temperature Sensor - wire open, short circuit, temperature sensor damaged, or Main PCB damaged (secondary error, only displayed via key combination).

First step from the service manual

Check for loose connections at CON5, damage on wires, and resistance value between brown to brown wires.

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

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What Er rt means on a LG refrigerator

The Er rt code indicates the control board has detected a fault in the room temperature sensor circuit, caused by either a short circuit or an open circuit (disconnection) in the sensor or its wiring. The room temperature sensor monitors ambient air temperature inside the refrigerator compartment and feeds that data to the control board to regulate cooling cycles. When the board reads a signal that falls outside the expected resistance range, whether from a shorted sensor pulling the reading too low or a broken connection sending no signal at all, it logs Er rt and halts normal temperature-based decisions for that sensor.

For homeowners, think of the room temperature sensor as a thermometer the refrigerator uses to decide when to run the compressor and fans. When this sensor fails or its wiring comes loose, the fridge no longer has accurate temperature data for that zone. The refrigerator may overcool, undercool, or behave erratically because it is working without reliable information. The error code is the fridge's way of flagging that a specific sensor input is missing or corrupted so the problem can be identified and fixed before food is compromised.

Source: manufacturer service documentation.

Common causes of Er rt

  1. 01

    Disconnected room temperature sensor connector

    Wiring / connection

    The sensor's wiring connector can work loose from vibration or handling during previous repairs. A disconnected connector creates an open circuit, which the control board reads as Er rt.

  2. 02

    Failed room temperature sensor

    Part replacement

    The sensor itself can fail internally, either shorting out or losing continuity. A faulty sensor will produce a resistance reading outside the acceptable range, triggering the error regardless of wiring condition.

  3. 03

    Damaged wiring harness to room temperature sensor

    Part replacement

    The wiring between the sensor and the control board can fray, pinch, or corrode, creating either a short or an open circuit. Inspect the full length of the harness for visible damage, especially near routing clips and door hinges.

  4. 04

    Faulty main control board

    Part replacement

    If the sensor and all wiring test within normal resistance specifications, the control board's input circuit for the room temperature sensor may have failed. This is the least common cause and should only be considered after the sensor and harness are confirmed good.

See the test procedure for each cause

Frequently asked questions about Er rt

What does Er rt mean on an LG refrigerator?
Er rt means the control board has detected a problem with the room temperature sensor, specifically a short circuit or a disconnection in the sensor or its wiring. The sensor is responsible for feeding ambient compartment temperature data to the control board. Without a valid signal from this sensor, the board cannot make accurate cooling decisions and displays Er rt to alert you to the fault.
How do I fix Er rt on an LG refrigerator?
Start by locating the room temperature sensor connector and checking that it is fully seated and undamaged. If the connector looks fine, use a multimeter to measure the sensor's resistance and compare it to the value listed in your model's service manual. A good sensor will show resistance within the specified range at a known temperature. If the sensor is out of spec, replace it. If the sensor tests good, inspect the wiring harness for damage between the sensor and the control board.
Can I still use my LG refrigerator when it shows the Er rt code?
The refrigerator may continue to run in a limited or degraded mode, but you should not rely on it to maintain safe food temperatures. Without accurate room temperature sensor data, the control board cannot regulate the cooling cycle correctly, meaning the compartment may be warmer or colder than the display shows. Check the actual internal temperature with a standalone thermometer and address the error promptly, especially if you are storing perishable food.
How much does it cost to fix the Er rt error code on an LG refrigerator?
If the fix is simply reseating a loose connector, there is no parts cost. A replacement room temperature sensor typically costs between $15 and $40 for the part. A replacement wiring harness can range from $20 to $60. If the control board is at fault, board replacement can run $100 to $250 or more for the part alone. Professional labor generally adds $80 to $150 per hour, so diagnosing and replacing a sensor is a repair many technically inclined homeowners can handle themselves to avoid that cost.
How do I test the room temperature sensor on an LG refrigerator showing Er rt?
Disconnect the sensor from its wiring harness and use a multimeter set to measure resistance. At room temperature, most LG room temperature sensors read in a predictable range specified in the service manual for your model. If the sensor reads zero ohms, it is shorted. If it reads infinite resistance or open loop, it is disconnected internally and must be replaced. Compare your reading to the spec before ordering parts to confirm the sensor is the actual cause of the Er rt code.

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