What E251 means
The discharge sensor monitors the hot gas leaving the compressor. If it fails, the board cannot protect the compressor from overheating, so it stops with E251.
Samsung AC E251 Error — Discharge Temperature Sensor Fault & Fix
E251
Quick answer
E251 means the compressor discharge temperature sensor has an open or short circuit on the outdoor unit.
What does the E251 code mean?
E251 is a compressor discharge temperature sensor error (open or short). The outdoor unit cannot monitor compressor outlet temperature.
Common causes
- Defective discharge thermistor
- Connector loose on the outdoor inverter or main PCB
- Wire melted or damaged from compressor heat
- PCB fault
Advertisement · In-content
How to fix the E251 error
Power off
Isolate at the breaker and wait for the compressor to cool.
Locate the sensor
The discharge sensor is clamped to the compressor discharge pipe — the hottest pipe on the outdoor unit.
Inspect wiring
Check for heat damage or melting near the compressor.
Check connector
Reseat at the PCB.
Measure resistance
Replace if outside the 10 kΩ range at 25°C.
Safety first: The discharge pipe can exceed 100°C during operation. Let the compressor cool for at least 15 minutes before touching.
Part you may need: Discharge temperature sensor (NTC thermistor)
Use high-temperature rated wire ties when routing the replacement sensor near the compressor.
Frequently asked questions
Why is the discharge sensor important?
It prevents compressor burnout by shutting down if the discharge gas gets too hot.
Can low refrigerant cause E251?
Low refrigerant causes high discharge temperatures (a different error), but does not cause the sensor itself to fail.
