P050FBrake Assist Vacuum Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- GM (from about model year 2017/18) monitors the brake booster with a vacuum sensor: with the pedal at rest and high intake vacuum the booster must hold its vacuum; a loss over time is filtered as a drift ratio, and above a threshold P050F sets, MIL after two trips. It runs with the engine on, during start-stop auto-stops and after switch-off. Without enough brake vacuum the module must throttle, restart the engine from auto-stop or request a pump – which affects idle and start-stop – and brake assistance can drop. Ford and FCA do not use P050F.
- What you may notice
- Check engine light on
- Hard brake pedal, especially after auto-stop
- Hissing at the pedal, start-stop stops less often
- Likely causes
- LikelyLeaking vacuum hose or check valve
- PossibleLeaking diaphragm in the brake booster
- PossibleVacuum sensor or its seal faulty
- RareElectric or mechanical vacuum pump weak (where fitted)
- 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: €20 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.