LG Refrigerator Error Code Er rt

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.

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.

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.

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.

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.