P0446
Evaporative Emission Vent Control Circuit Malfunction
A fault in the EVAP vent valve circuit. The vent valve seals the canister against atmosphere during the leak test; without it, the test cannot pull a vacuum and may set false leak codes alongside.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Common causes
Ordered by how often each turns out to be the cause.
- Vent valve seized or contaminated by water/dirtCommon
- Wiring or connector faultPossible
Parts involved
- EVAP Vent Valve
- EVAP Vent Valve Wiring
P0446 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.