P051F
PCV Filter Restriction
The pressure or flow sensor in the PCV path detects increased restriction across the oil-mist filter element. Once saturated with oil mist, the filter no longer passes blow-by gas, raising crankcase pressure and pushing oil past seals.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
Common causes
Ordered by how often each turns out to be the cause.
- PCV filter saturated with oil mistCommon
Parts involved
- PCV Filter
- Crankcase Pressure Sensor A
P051F is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.