LG Air Conditioner Error Code 231

Error code 231 indicates a temperature sensor fault at the sub-cooling discharge pipe on HR unit 8. The system has detected either an open circuit or a short circuit in that sensor circuit. This prevents the unit from accurately monitoring refrigerant conditions in that zone, causing it to stop operating. The fault is most often traced to a loose connector, damaged wiring, or a failed thermistor.

The system will typically suspend normal operation when this error is active to protect components from running without accurate temperature data. Attempting to bypass or ignore this fault and force the unit to run is not recommended, as the sub-cooling circuit can be damaged if refrigerant temperatures go unmonitored. Address the sensor fault before resuming normal operation.

A power reset may temporarily clear the error code, but if the underlying sensor or wiring fault is still present, the code will return as soon as the system runs and the control board polls that sensor again. A reset is useful for confirming whether the fault is intermittent, but it is not a repair. The sensor connection and wiring should be inspected and tested to resolve the issue permanently.

Start by inspecting the sensor connector and lead cable for HR unit 8 as the first diagnostic step. Check that the connector is fully seated, pins are clean and undamaged, and the cable has no visible cuts or pinching. If the wiring looks intact, use a multimeter to measure thermistor resistance at the sensor and determine whether the sensor has failed and needs replacement.

If the fix is simply reseating a loose connector, the cost is minimal, essentially just a service call fee in the range of $75 to $150. If the temperature sensor requires replacement, parts and labor typically range from $150 to $350 depending on the specific unit and labor rates in your area. Control board replacement, if required, is significantly more expensive and can range from $400 to $800 or more.