The P2518 code indicates that the vehicle's control module detected a high voltage signal from the refrigerant pressure sensor B circuit. This sensor monitors the pressure of the A/C system's high side. When the signal is outside the normal range, the code is set.
The sensor can fail internally and output a voltage that the PCM interprets as high pressure.
Damaged insulation or a short in the sensor circuit can raise the signal voltage above normal.
Over‑charged or blocked condenser can cause actual high pressure that the sensor correctly reports.
A rare failure of the PCM's sensor input circuit can misinterpret normal sensor voltage as high.
Replacing the PCM is rarely necessary; the issue is usually a faulty sensor, wiring problem, or abnormal system pressure.
Excessive pressure can strain components and may cause the A/C system to shut down, but it is not an immediate safety hazard if the vehicle is driven briefly.
Yes, proper recovery and disposal of refrigerant is required by law before disconnecting any A/C components.
Only if the inspection reveals an obvious wiring fault; most cases require functional testing of the sensor and pressure check.