Samsung Air Conditioner Error Code E257

E257 indicates a fault with the discharge temperature sensor on fixed scroll compressor 2. The sensor circuit voltage is reading either above 4.95V (open circuit, indicating broken or disconnected wiring) or below 0.5V (short circuit, indicating a shorted sensor or wiring). The system cannot verify safe compressor operating temperatures and shuts down the affected compressor until the fault is resolved.

No. The discharge temperature sensor protects the compressor from overheating by providing real-time temperature data to the control system. With this sensor reading invalid data, the system cannot detect an over-temperature condition on compressor 2, which could result in compressor damage or failure if the unit were forced to operate. The system typically disables the affected compressor automatically, and the unit should be serviced before returning to normal use.

Repair costs vary depending on what failed. If the issue is simply a loose connector or a broken wire that can be repaired without new parts, labor charges for a service call could range from roughly 80 to 200 dollars. If the discharge temperature sensor itself needs replacement, parts and labor combined typically range from 150 to 400 dollars or more, depending on the unit model and local labor rates. A control board replacement, if required, would be at the higher end of the cost range.

A knowledgeable DIYer can inspect the sensor wiring harness and connector for obvious damage such as broken wires or a dislodged connector plug. However, accessing the compressor discharge sensor on a multi-compressor commercial or multi-zone unit typically requires opening refrigerant-side panels and working near high-voltage components, which is best left to a licensed technician. Replacing the thermistor sensor itself also requires correctly identifying and sourcing the right part for the specific compressor model.

A power reset may temporarily clear the error code from the display, but if the underlying fault in the sensor circuit has not been repaired, the error will return as soon as the system attempts to read the sensor again. A reset alone does not fix a broken wire, corroded connector, or failed thermistor. The wiring and sensor must be inspected and repaired before the unit will operate reliably without the fault reappearing.