P0446 — Evaporative Emission System Vent Control Circuit
Low severityWhat it means
P0446 is stored when the engine control unit sees a fault involving the EVAP vent control valve circuit. The vent valve lets fresh air into the EVAP charcoal canister and seals the system closed for leak tests; the control unit controls it. The control unit has flagged this circuit or signal as outside its normal operating range.
Common symptoms
- Usually only a check engine light
- Hard refuelling if the valve sticks closed
- Failed emissions inspection
Likely causes
- A wiring, connector or ground problem in the circuit
- A failed sensor or actuator in the circuit
- A stuck or failed vent valve
- A wiring or connector fault, sometimes from corrosion under the car
What to check first
- Inspect the connector and wiring for damage, corrosion or loose pins
- Command the vent valve with a scan tool and confirm it operates
- Inspect the valve and connector, which are often near the tank
Can you keep driving?
Safe to drive; it is an emissions fault, but the car will fail an emissions test until repaired.
Frequently asked questions
What is the most common cause of P0446?
The most likely cause is: A wiring, connector or ground problem in the circuit. Several other faults can set P0446 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0446 and keep driving?
Clearing P0446 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0446?
P0446 is a low-severity code. It rarely affects how the car drives, but it is still worth fixing so the engine runs efficiently and passes an emissions test.
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