Evaporative emission (EVAP)
P0446 — Evaporative Emission System Vent Control Circuit
The ECU detected a fault in the EVAP vent control circuit. The vent valve opens the canister to fresh air; if it is stuck or electrically faulty, the system cannot be tested or purged correctly.
Common causes
- Faulty vent valve (solenoid)
- Blocked vent line or canister inlet (dirt, insects, water)
- Damaged wiring or connector
- Corrosion on the valve
- Engine control module driver fault (rare)
Symptoms
- Check engine light
- Difficulty filling the fuel tank (pump clicks off early)
- Fuel smell
- Failed emissions test
How to check
- Check the vent valve connector and wiring
- Command the valve with a scan tool and verify it opens and closes
- Check the vent line and canister inlet for blockage
- Replace the vent valve if it sticks
Can you keep driving?
Usually safe to drive. The valve is part of the emissions system; repair it at a convenient time.
Related codes
Frequently asked questions
- What does P0446 mean?
- The ECU detected a fault in the EVAP vent valve or its control circuit.
- Why does P0446 make refuelling difficult?
- A stuck-closed vent valve prevents the tank from venting, so the pump nozzle keeps clicking off.
General reference information. It does not replace a diagnosis on your own vehicle. The same code can have different causes depending on make, model year and engine; check the manufacturer's documentation or ask a technician with a scan tool.