OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

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.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 18

Possible causes

  • Signal wire shorted to reference voltage high
  • Open signal return at the sensor medium
  • Connector pins corroded - high contact resistance low

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 80–400 €
  • Estimated time: 0.4–1.5 h
  • Component: ac pressure sensor b
  • Component: sensor wiring
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication