P04FB
Crankcase Ventilation Hose Connection Sensor Range/Performance
Generic OBD-II
Real-world scan data
Seen in
39
scans in the past year
Found in
<0.1%
of scans
<0.1%
of scans that found faults
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check and clean or replace the PCV valve
- Inspect and repair any vacuum leaks
- Replace faulty crankcase ventilation system components
- Check piston ring blow
- by
- Inspect and replace the PCV filter
Common causes
Most likely first
- Loose or disconnected crankcase ventilation hose
- Clogged or blocked crankcase ventilation hose
- Malfunctioning crankcase ventilation sensor
- Faulty sensor wiring or connectors
- Engine vacuum leak
How to diagnose & fix
Work through it in order
- Engine misfires or runs rough
- Decreased engine power or acceleration
- Increased fuel consumption
- Engine stalling or rough idle
- Check Engine Light (MIL) illuminates
Read & clear P04FB yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.