LG Heat Pump Error Code sx

The SX code on an LG heat pump is a protection alert that appears when the unit detects that outdoor conditions are outside the acceptable range for heating operation. It activates when outdoor ambient temperature exceeds 30°C during a heating request, or when refrigerant charging in heating mode is attempted with the outdoor unit temperature above 15°C. The flickering display is intentional and indicates a protective hold rather than a component failure.

No, SX is not a safety hazard. It is a built-in protective feature that prevents the heat pump from running heating mode under conditions that could reduce efficiency or cause refrigerant circuit stress. The unit is functioning exactly as designed when this code appears.

In the vast majority of cases, there is no repair cost because SX is a protection feature, not a defect. If a faulty outdoor temperature sensor is causing a false SX code, sensor replacement and labor could range from roughly $100 to $300 depending on the technician and the specific unit. Always confirm the outdoor temperature conditions first before scheduling a service call.

In most cases, no repair is needed. If the code appeared during hot weather, simply wait for outdoor temperatures to drop below 30°C and heating operation will resume automatically. If the code appeared during a refrigerant charge, the technician should adjust the charging conditions or allow the outdoor unit to cool below 15°C before continuing. If SX persists during cool weather, inspect the outdoor ambient temperature sensor for faults.

A manual reset will not permanently clear the SX code if the outdoor temperature is still above the threshold. The code will return immediately because the protection logic re-evaluates conditions continuously. The code will only clear and stay clear once the outdoor ambient temperature drops below 30°C for a heating operation hold, or below 15°C for a refrigerant charging hold.