P0555Brake Booster Pressure Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Needs a drive cycle to confirm a fix
- How the car detects it
- The brake booster pressure sensor (5 V reference, signal, ground) measures the vacuum in the brake booster. On direct-injection, turbo, stop-start and hybrid engines intake vacuum is scarce, so the engine module watches it and creates vacuum when needed – closing the throttle, suppressing engine stop or running an electric vacuum pump. That makes it an input to idle and throttle control. P0555 is the general circuit fault without low/high distinction. No manufacturer document available to us uses it; GM splits circuit faults into P0557 and P0558. The module then assumes a substitute value and keeps vacuum available as a precaution.
- What you may notice
- Check engine light or brake booster warning
- Stop-start inactive
- Often no change in driving
- Likely causes
- LikelyConnector or wire to the sensor open or corroded
- PossibleSensor faulty
- Possible5 V reference disturbed (short at another sensor on the same reference)
- RareEngine module
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.