What P050F means
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.
How the engine computer detects it
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.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Hard brake pedal, especially after auto-stop
- Hissing at the pedal, start-stop stops less often
Common causes
- Leaking vacuum hose or check valve Most likely
- Leaking diaphragm in the brake booster Possible
- Vacuum sensor or its seal faulty Possible
- Electric or mechanical vacuum pump weak (where fitted) Less likely
How to diagnose P050F
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: brake booster, brake booster vacuum sensor, vacuum hose, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P050F most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| GMC Terrain | 2018–2019 | 3 | — |
Counts of owner complaints to the NHTSA that mention P050F (6 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 5
- Vehicle speed, idle control and auxiliary inputs
- 0F
- Specific fault
Questions drivers ask
Can I drive with code P050F?
Usually yes, carefully. Your hydraulic brakes normally keep working, but ABS, traction and stability control may be off, so the wheels can lock in a hard stop. If the red brake warning light is on, the pedal feels soft or different, or the car takes longer to stop, don't drive: have it towed.
Will my car pass an emissions inspection with P050F?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P050F clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P050F myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.