OBD-II code · Powertrain (generic, extended)
P25C4 Brake Booster Temperature Sensor A Circuit
The temperature sensor monitoring the electric brake booster (iBooster, eBooster) returns no usable signal. Without temperature feedback the controller derates booster assist to protect the motor.
Is it safe to drive with P25C4?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyOpen sensor element or broken sensor wire
- PossibleCorroded connector on the booster sensor pigtail
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Electric Brake Booster, Temperature Sensor, Wiring Harness
Related codes
- P25C1Alternative Fuel Disable Signal Circuit
- P25C2Alternative Fuel Disable Signal Circuit High
- P25C3Alternative Fuel Disable Signal Circuit Low
- P25C5Brake Booster Temperature Sensor A Circuit Range/Performance
- P25C6Brake Booster Temperature Sensor A Circuit Low
- P25C7Brake Booster Temperature Sensor A Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.