OBD-II code · Powertrain (generic)
P05D9 PCV Regulator Valve Control Circuit Low
Same as P05D8 with the control line shorted to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P05D9?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl line shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.4–1.5 h
- Emissions test
- Likely to fail
- Parts involved
- Pcv Regulator Valve
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.