LG Heat Pump Error Code E251

E251 on an LG heat pump indicates a discharge temperature sensor error on fixed capacity compressor 1. The control board has detected that the sensor signal is either completely absent (OPEN) or shorted, and the fault is active when the outdoor temperature is above -10 degrees Celsius. The system shuts down to prevent compressor damage until the fault is resolved.

No, the system will generally prevent normal operation when E251 is active because the discharge sensor is a critical protection input for the compressor. Attempting to bypass or ignore the fault risks operating the compressor without proper temperature monitoring, which could lead to overheating and compressor failure. Allow the system to remain off until the fault is diagnosed and repaired.

Repair costs vary depending on what component has failed. A replacement discharge temperature sensor typically costs between 20 and 80 dollars for the part, with labor adding another 75 to 150 dollars depending on your location and the technician's rates. If the outdoor control board is the root cause, parts alone can range from 150 to 400 dollars or more, making total repair costs significantly higher.

A knowledgeable DIYer can perform basic checks such as inspecting the sensor connector for loose connections or visible damage and reseating any disconnected plugs. However, measuring sensor resistance accurately, tracing wiring faults, and replacing components inside the outdoor unit typically require familiarity with heat pump systems and a multimeter. If the sensor or control board needs replacement, a qualified HVAC technician is recommended.

A power reset may temporarily clear the error code from the display, but if the underlying sensor or wiring fault still exists the error will return once the system attempts to operate and the control board re-checks the sensor signal. A reset alone is not a repair, and the fault should be properly diagnosed before relying on the system for heating or cooling.