An E251 error could point to the discharge temperature sensor, which monitors how hot the refrigerant gas is as it leaves the compressor. This is an important safety reading, and an open or short circuit at this sensor means the system can no longer confirm the compressor is operating within a safe temperature range.
Because overheating at the discharge line can indicate a serious underlying issue if left unmonitored, the unit will shut down rather than keep running blind. In most cases though, the fault is with the sensor or its wiring rather than the compressor itself.
Send us the code and a photo of the display, and a Ford & Doonan technician will get back to you. Please don't reset the unit before you take the photo.
(08) 9331 8800