P2518
A/C Refrigerant Pressure Sensor B Circuit High
A/C & climate control
Generic OBD-II
Low
What it means
P2518 means the "B" air-conditioning refrigerant pressure sensor circuit is reading a higher voltage than expected. The computer uses this sensor to control the A/C compressor and cooling fans, so the fault is almost always in the sensor or its wiring. It affects air conditioning, not how the engine runs.
Low
Can I keep driving? Safe to drive. The engine runs normally; you may just lose air conditioning or notice the cooling fans and A/C compressor behaving oddly.
Common symptoms
What you'll notice
- Check-engine light on
- Air conditioning weak or not working
- A/C compressor not engaging
- Cooling fans running when not expected, or not at all
Common causes
Most likely first
- A/C refrigerant pressure sensor 'B' signal wire shorted high or openLikely
- Faulty A/C refrigerant pressure sensorCommon
- Corroded or loose sensor connectorCommon
- Open reference or ground causing a high readingLess often
- Refrigerant charge far out of spec (over- or under-charged)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check the live A/C pressure sensor value against system pressure.
- Inspect the sensor connector and wiring for corrosion, an open, or a short to voltage.
- Verify the 5-volt reference and ground reach the sensor.
- Compare sensor output to a manifold gauge reading; a mismatch points to the sensor.
- Replace the pressure sensor if wiring is good, then clear and verify A/C operation.
FAQ
Quick answers
Is it safe to drive with P2518?+
Yes. This is an A/C circuit code and doesn't affect how the engine runs — you may just lose cooling until it's fixed.
Can I just clear P2518?+
It clears, but returns until the sensor or its wiring is repaired. It won't harm the engine to keep driving in the meantime.
Related codes
Often seen with P2518
Read & clear P2518 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX