Samsung Air Conditioner Error Code 257

Error code 257 indicates that the discharge temperature sensor for fixed scroll compressor 2 has an open or short circuit fault. The control board is reading a voltage either above 4.95V or below 0.5V on that sensor circuit, which corresponds to physically impossible temperatures of -30 degrees Celsius or 151 degrees Celsius respectively. This means the sensor signal is not valid, and the system has flagged the fault to prevent unprotected compressor operation.

It is not recommended to continue running the unit with error code 257 active. The discharge temperature sensor protects compressor 2 from thermal overload, and without a valid sensor reading the system cannot enforce that protection. Operating without this safeguard risks serious compressor damage, which can be a much more costly repair than addressing the sensor fault.

A power reset may temporarily clear the error code, but it will return immediately if the underlying wiring or sensor fault is still present. The system continuously monitors the sensor voltage during operation, so any open or short circuit condition will retrigger the fault code. The physical fault must be diagnosed and corrected before the error will clear permanently.

Some basic checks, such as verifying that the sensor connector is fully seated and that no wires are visibly pinched or broken, can be performed by a careful DIYer. However, accessing the discharge temperature sensor on a fixed scroll compressor typically requires disassembling internal panels and working near high-voltage components. Most repairs beyond a simple connector reseating should be performed by a qualified HVAC technician.

Repair costs vary depending on the root cause. If only a connector needs reseating, a service call fee may be the only expense, typically in the range of $75 to $150. Replacing a discharge temperature sensor generally costs between $150 and $350 including parts and labor. If the control board is the cause, costs can rise to the $400 to $800 range or higher depending on the model and board availability.