P2515: Air Conditioning Refrigerant Pressure Sensor B Circuit
What to do
Expect the air conditioning to stop working or to cut in and out. Worth attending to before hot weather or heavy traffic for a reason beyond comfort: the module uses this reading to decide cooling fan speed, and those fans cool the engine as well as the condenser. If the temperature gauge climbs in slow traffic, do not dismiss it as unrelated.
What this code means
A fault in the circuit of the second air conditioning refrigerant pressure sensor.
Air conditioning pressure is not only an air conditioning matter, which is why an engine code exists for it. The engine control module uses refrigerant pressure for several decisions that have nothing to do with cabin comfort:
- Cooling fan speed. High refrigerant pressure means the condenser needs airflow, so the fans are commanded up — and the same fans cool the engine. A pressure sensor fault can therefore leave an engine short of cooling in traffic, which is a more serious consequence than a warm cabin.
- Compressor engagement. The compressor is disengaged at extremes of pressure to protect itself, and momentarily under hard acceleration to return its power to the wheels.
- Idle speed. The compressor is a substantial load, and the module raises idle to absorb it.
A second sensor implies the system measures both sides of the circuit, and as elsewhere in this corpus the pair is more informative than either alone: the difference across the compressor is what indicates whether the refrigerant charge is correct. That is the same structural idea as the paired coolant sensors at P2182 and the paired NOx sensors at P2200 — one sensor gives a value, two give a measurement.
Likely causes
Start here
- Faulty air conditioning refrigerant pressure sensor · easy
- Corroded or loose connector · easy
- Damaged wiring harness · moderate
Less common
- Low refrigerant charge · moderate
- Failed sensor reference voltage supply · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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