P0559Brake Booster Pressure Sensor Circuit Intermittent
- 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. P0559 means the signal jumps briefly – a loose contact or broken wire under movement – without staying out of range long enough for P0557 or P0558. No manufacturer document available to us uses it; GM catches dropouts through the sample counters of P0557/P0558. CARB requires input components to be checked for circuit faults.
- What you may notice
- Warning comes and goes
- Stop-start inactive at times
- Check engine light (depending on the maker)
- Likely causes
- LikelyLoose contact at the sensor connector (pin tension, corrosion)
- PossibleBroken or chafed wire moving with the engine
- RareSensor with internal dropouts
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.