OBD-II code · Powertrain (generic)
P04DB Crankcase Ventilation System Disconnected
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 with P04DB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyPCV hose pulled off or split
- PossibleOil filler cap missing or loose
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1 h
- Emissions test
- Likely to fail
- Parts involved
- Pcv Hose, Pcv Valve, Pcv Sensor
Related codes
- P04D8Excessive Time To Enter Closed Loop EGR Control
- P04D9Closed Loop EGR Control At Limit Flow Too Low
- P04DAClosed Loop EGR Control At Limit Flow Too High
- P04DCFuel Fill Door Position Sensor Circuit Range or Performance
- P04DDCold Start EGR A Flow Insufficient Detected
- P04DECold Start EGR A Flow Excessive Detected
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.