P0446: Evaporative Emission System Vent Control Circuit
P0446 means Evaporative Emission System Vent Control Circuit. The engine computer has found a fault in the canister vent valve control circuit, or the vent is blocked. The control module has detected a fault in the circuit itself, such as an open circuit, a short, or a signal outside the electrical limits it expects.
Can I keep driving? Safe to drive short-term, but have it checked to avoid failed emissions or worse fuel economy.
Common symptoms
- Check engine light on
- Usually no drivability change
- Possible hard starting after refuelling (purge valve stuck open)
Possible causes
- Failed purge or vent solenoid
- Wiring or connector fault
- Blown fuse
- Failed EVAP pressure sensor (sensor codes)
- Blocked canister vent (vent codes)
How to diagnose P0446
- Inspect the connector and wiring.
- Measure solenoid resistance and compare with specification.
- Command the solenoid on a scan tool and listen/feel for clicking.
- Check power supply and ground.
What the code means, digit by digit
Generic codes have the same definition on every OBD-II vehicle (petrol cars from model year 1996 in the US, 2001 in the EU; diesels later). Manufacturers can add their own enhanced codes; those are not listed here.
Related codes
- P0443 Evaporative Emission System Purge Control Valve Circuit
- P0449 Evaporative Emission System Vent Valve/Solenoid Circuit
- P0441 Evaporative Emission System Incorrect Purge Flow
- P0451 Evaporative Emission System Pressure Sensor/Switch Range/Performance
- P0452 Evaporative Emission System Pressure Sensor/Switch Low
- P0453 Evaporative Emission System Pressure Sensor/Switch High
- P0496 Evaporative Emission System High Purge Flow
- P0497 Evaporative Emission System Low Purge Flow
General guidance only. Fault codes describe what the engine computer saw, not which part failed: confirm with testing before replacing parts, and follow the vehicle's service information.