LG Refrigerator Error Code R1 R2 R3 ON

The R1 R2 R3 ON error on an LG refrigerator indicates an open or short circuit condition in the ambient room temperature (RT) sensor. This sensor monitors the surrounding environmental temperature so the refrigerator's control board can adjust compressor and fan operation accordingly. When the control board detects a signal from the RT sensor that falls outside the expected resistance range, it flags this error to alert the technician that sensor data cannot be trusted.

Ambient temperature sensors in LG refrigerators are typically negative temperature coefficient (NTC) thermistors, meaning their resistance decreases as temperature increases. An open circuit occurs when the sensor or its wiring has a break, causing resistance to read abnormally high or infinite. A short circuit occurs when the sensor leads contact each other or a grounded surface, driving resistance near zero. Either condition prevents accurate temperature readings.

The R1, R2, and R3 designations appearing together indicate the error is being flagged across multiple display segments or diagnostic indicators simultaneously rather than pointing to three separate sensors. Initial diagnosis should focus on physically inspecting the RT sensor and its wiring harness for damage, corrosion, or loose connector pins. The sensor itself should be tested with a multimeter to verify its resistance value falls within the expected range for the current ambient temperature.