Samsung Heat Pump Error Code E251

E251 indicates a digital compressor discharge temperature sensor breakaway fault. The system detected that the CT sensor was reading above 5A, confirming the compressor was under load, while the discharge temperature sensor read below the high pressure saturation temperature for more than 30 minutes. This contradiction points to the discharge temperature sensor losing proper contact with the discharge line.

Operating the system with a detached or malfunctioning discharge temperature sensor is not advisable. The discharge temperature sensor is part of the compressor protection circuit, and running without accurate discharge temperature data can allow the compressor to operate outside safe temperature limits without triggering protective shutdowns. The system should be inspected and the fault resolved before continuing normal operation.

If the fix is simply reseating the sensor in its holder, the cost is primarily a service call fee, typically in the range of $75 to $150 depending on your location. If the sensor holder or the discharge temperature sensor itself needs replacement, parts and labor combined generally range from $100 to $300. More extensive diagnosis involving wiring or control board issues can increase costs further.

The first diagnostic step, checking whether the discharge temperature sensor and its holder are attached correctly, is something a knowledgeable DIYer can perform with a visual inspection. However, if the sensor needs resistance testing, the wiring requires diagnosis, or refrigerant system conditions are involved, a certified HVAC technician should handle the repair. Working around compressor discharge lines also involves high temperatures and pressures that require proper safety precautions.

A reset may temporarily clear the fault code, but E251 will return if the underlying cause is not corrected. The fault requires the abnormal condition to persist for over 30 minutes, so the error will reappear once the system runs through another full operating cycle with the sensor still improperly seated or malfunctioning. Fixing the sensor attachment or replacing the faulty component is necessary for a lasting resolution.