Code result
P04FC
Crankcase Ventilation System Performance
Moderate severity
What it means
A general performance fault of the crankcase ventilation system - PCV pressure or flow does not match the engine model. Possible causes are a clogged PCV valve, blocked separator, oil-filler cap with a damaged seal, or excessive blow-by from worn rings.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
PCV valve clogged or stuck
highOne of the most commonly reported causes for this code — check this first.
Oil separator clogged
mediumA plausible cause — test and verify before replacing parts.
Excessive blow-by from worn piston rings
lowLess common, but worth ruling out after the more likely causes.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P04FC freeNo credit card required