P25F5Turbocharger/Supercharger Boost Sensor C Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P25F5 reports a signal from boost sensor C above the highest plausible value. Since the voltage climbs with pressure, a reading at the top end usually means an electrical fault: the signal shorted to 5 V or battery voltage, an open sensor ground, or an open signal wire where the input is pulled up. The limits differ widely by engine – for sensor A, Saab's GM-based 1.6 litre sets its code above 4.8 V (4 s at a stretch or 50 s cumulated, type C without lamp), whereas the 2.0 litre already flags a reading above 3.9 V lasting 5 s as a type B fault. No manufacturer documents these limits for sensor C. Because the engine would believe boost is excessive, it typically cuts boost control. P25F4 is the opposite fault.
- What you may notice
- Check engine lamp on, depending on the manufacturer
- Reduced power, boost cut back
- Likely causes
- LikelySensor ground open or high resistance
- PossibleSignal wire shorted to 5 V or battery voltage
- PossibleBoost sensor C failed internally
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.