P2518
A/C Refrigerant Pressure Sensor B Circuit High
A/C refrigerant pressure sensor B signal voltage reads above the upper limit. Typically a short to reference voltage in the signal line, an open signal return, or an overpressure event briefly pegging the sensor. ECM disables variable compressor control to protect the system.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Signal wire shorted to reference voltageCommon
- Open signal return at the sensorPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- AC Pressure Sensor B
- Sensor Wiring
P2518 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.