P0558Brake Booster Pressure Sensor Circuit High
- 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. P0558 means the signal voltage is too high: GM 2018 above 95 % of the reference in 2000 of 2400 samples (about 30 s), GM 2006 above 4.89 V; type B, two trips. Typical are a signal shorted to 5 V or battery voltage or an open sensor ground. A real loss of vacuum does not set P0558 but P0556 or, depending on the maker, P050F.
- What you may notice
- Check engine light or brake booster warning
- Stop-start inactive
- Often no change in driving
- Likely causes
- LikelySensor ground open (connector, wire)
- PossibleSignal shorted to 5 V reference or battery voltage
- PossibleSensor faulty
- RareEngine module
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.