Can drive — fix at your convenience.
P0446 means there's a problem in the vent control circuit, the part of the EVAP system that lets fresh air into the charcoal canister so it can do its job. The fault is usually a stuck or failed vent valve, a wiring or connector issue, or debris blocking the valve. The car runs normally, but the system can't properly manage fuel vapors.
$100 – $400
Varies by vehicle and root cause.
Usually not for this code. P0446 points to the vent valve or its wiring rather than the gas cap. It's still worth checking the cap is tight, but the fix more often involves cleaning or replacing the vent valve.
Yes, in most cases. The car drives normally. The main inconvenience is that refueling may be slow, and the check engine light stays on, so get it looked at before too long.
A new vent valve plus diagnosis and labor typically runs $100-400, depending on the vehicle and whether wiring repair is needed.
It's low severity. It won't damage the engine, but a malfunctioning vent valve can make fueling annoying and prevents the EVAP system from working correctly, so it should be repaired.