LG Refrigerator Error Code R1 R2 R3 R4

These codes all indicate a fault with the refrigerator compartment temperature sensor. The sensor is either shorted, causing 0V at the diagnostic test point, or has an open circuit, causing 5V at that same point. The normal operating range at Point A is 0.5V to 4.5V. When this fault is present, the compressor defaults to a 15-minute ON and 15-minute OFF cycle because the control board cannot receive accurate temperature data.

The refrigerator will continue to run in a failsafe mode with the compressor cycling 15 minutes on and 15 minutes off, but it will not accurately regulate temperature. This means the interior temperature may not stay within the safe range for perishable food. It is advisable to address the fault promptly and monitor food temperatures closely in the meantime.

If only the temperature sensor needs replacement, parts costs typically range from around $15 to $60 depending on the model, with professional labor adding $80 to $200 or more depending on your location. If the fault turns out to be a wiring or connector issue, repair costs may be lower since no major parts are required. Control board replacement, if needed, is significantly more expensive and can range from $150 to $400 or higher for parts alone.

A knowledgeable DIYer can diagnose this fault by measuring voltage at Point A in the sensor circuit and checking the sensor resistance directly. If the sensor wiring or connector is visibly damaged or corroded, that can sometimes be repaired without special tools. However, if the thermistor itself has failed, a replacement sensor will be needed, and the part must be compatible with your specific LG model.

A power reset may temporarily clear the displayed code, but if the underlying sensor fault is still present, the code will return once the control board re-evaluates the sensor signal. The fault must be corrected by repairing or replacing the faulty sensor or wiring before the error will clear permanently.