P0447EVAP System Vent Control Circuit Open
- 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
- The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. P0447 belongs to the older scheme for the vent valve circuit (P0446 circuit, P0447 open, P0448 shorted), used by Subaru (also in the Saab 9-2X), VW and Nissan; GM reports an open vent circuit as P0449, Ford as P0446. On Subaru the valve is fed from the main relay and switched to ground by the module; if the voltage at the module output is missing or the coil is high-resistance (nominal 10–100 Ω), the code sets after two consecutive drives. The valve stays in its rest position and the leak test cannot run.
- What you may notice
- Check engine light on
- EVAP leak test does not run, readiness not set
- Usually no change in driving
- Likely causes
- LikelyVent valve connector corroded or off (underbody, splash water)
- PossibleVent valve coil open (resistance outside 10–100 Ω)
- PossibleWire to the module or supply from the main relay open
- RareEngine module or its connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €30 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.