Code result
P04DB
Crankcase Ventilation System Disconnected
Moderate severity
What it means
A pressure or flow sensor in the crankcase ventilation (PCV) circuit reports atmospheric conditions where it should see crankcase or intake vacuum - the hose between crankcase and intake is disconnected, cracked, or open. PCV no longer routes blow-by gases into the intake, increasing oil mist emissions and risking oil leaks.
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 hose pulled off or split
highOne of the most commonly reported causes for this code — check this first.
Oil filler cap missing or loose
mediumA plausible cause — test and verify before replacing parts.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P04DB freeNo credit card required