LG Refrigerator Error Code R0 R1 ON, R2-R4 OFF

The R0 R1 ON, R2-R4 OFF error code on an LG refrigerator indicates a refrigerator compartment sensor failure. Specifically, this code pattern signals that the sensor circuit within the refrigerator control box is experiencing either a short circuit or an open circuit condition. The refrigerator temperature sensor (thermistor) is a resistive device whose resistance changes predictably with temperature, and the control board monitors this resistance continuously to regulate cooling cycles. When the resistance reading falls outside the expected range due to a wiring fault, the board flags this error.

A shorted sensor circuit means the resistance has dropped abnormally low, often near 0 ohms, causing the control board to receive an out-of-range signal. An open circuit means the resistance has climbed toward infinity, typically due to a broken wire, corroded connector, or a failed thermistor. Both conditions prevent accurate temperature readings, which can cause the refrigerator to either overcool or fail to cool altogether. The fault is localized to the wiring and sensor assembly routed through the refrigerator control box, so inspection should begin at the harness connections and sensor terminals in that area.

Diagnosing this code requires a multimeter to check thermistor resistance at the sensor leads and continuity through the wiring harness. A healthy LG refrigerator thermistor typically reads within a specific resistance range that corresponds to the compartment temperature. Any reading far outside that range, or an open or shorted reading, confirms the fault. If wiring and connectors check out, the thermistor itself should be replaced. In some cases the control board may be at fault if it fails to read a known-good sensor correctly.