The crankcase ventilation has an oil mist separator or filter element that can clog; the crankcase pressure sensor then sees rising pressure at a given flow. P051F reports this restriction. No manufacturer document available to us uses it – Ford reports high pressure under P051B. BMW and GM bulletins describe the consequences of a blocked separator: oil pushed past seals, oil mist in the intake and charge air cooler, higher oil consumption. CARB requires the PCV system to be monitored.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Check engine light on
- Oil leaks at seals or dipstick
- Oil mist in the intake, higher oil consumption
Most likely causes
- Separator or filter clogged with oil, soot or sludge
- Icing in the separator or hose on short winter trips
- Oil change intervals exceeded (sludge)
- Pressure sensor reading wrong
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P051F means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 5: Speed and idle
- 1F: Specific fault in that system
Frequently asked questions
Can I keep driving with code P051F?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P051F?
The most common causes are: separator or filter clogged with oil, soot or sludge; icing in the separator or hose on short winter trips; oil change intervals exceeded (sludge).
Related codes
- P053ECrankcase Pressure Too High
- P052EPCV Regulator Valve Performance
- P051BCrankcase Pressure Sensor A Circuit Range/Performance
- P04DBCrankcase Ventilation System Disconnected
- P04FCCrankcase Ventilation System Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.