P2517: Air Conditioning Refrigerant Pressure Sensor B Circuit Low
What to do
Expect no air conditioning at all. The module is refusing to run the compressor deliberately, and that is protecting it — refrigerant carries the compressor's oil, so running one on an empty system destroys it. Ask for the system pressure to be measured before the sensor is replaced; a system that has lost its charge reads exactly like a shorted circuit, and the repair is the leak rather than the sensor.
What this code means
The second refrigerant pressure sensor circuit reads below its valid range — a short to ground, or a reported pressure below anything the system could physically hold.
That second case is worth separating, because a genuinely empty system reads at the bottom of the scale and is not a circuit fault at all. A system that has lost its entire charge — through a failed hose, a corroded condenser or a compressor seal — reports exactly this, and no amount of testing the wiring will find it.
The module's response is protective either way: the compressor is not engaged without a valid pressure reading, because running one without refrigerant destroys it. The refrigerant carries the compressor's lubricating oil, so an empty system running its compressor is a compressor running dry.
Likely causes
Start here
- Refrigerant leak · moderate
- Wiring shorted to ground · moderate
- Faulty air conditioning refrigerant pressure sensor · easy
Less common
- Corroded or loose connector · easy
- Corroded condenser · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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