P05D9PCV Regulator Valve Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some turbo engines have an electrically controlled crankcase ventilation valve that decides when and how much blow-by gas is drawn into the intake (part-load versus full-load path). The engine module monitors its driver output; CARB requires output components to be checked for circuit faults and the PCV system to be monitored. Nissan's 1.5 L KR15DDT (Rogue 2024–25) sets P05D8/P05D9 with the warning lamp from a severed harness at the valve; Mercedes M270/M274 have such a valve but report it under P052E. P05D9 means the control line is too low – a short to ground of the control or supply line, or with a low-side driver too low a voltage when off.
- What you may notice
- Check engine light on
- Often no noticeable symptoms
- If the valve sticks: oil mist, blue smoke, rough idle
- Likely causes
- LikelyDamaged harness shorted to ground
- PossibleValve shorted internally
- RareMoisture or oil in the connector
- RareEngine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.