P0446 on a Chevy: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Safe to drive, but fix the vent system soon if you notice fuel smells or trouble filling the tank.

What P0446 means on a Chevy

On a Chevy, P0446 means the vent valve that controls airflow into the EVAP canister is not working right — it is usually stuck or has a wiring problem. When the vent can't open, pressure builds in the tank, which can make filling slow. The engine runs normally, so the check engine light is the main symptom.

Is P0446 common on Chevys?

P0446 shows up on Chevys like the Silverado, Equinox, and Malibu as the canister vent valve ages. On GM trucks the vent valve sits near the charcoal canister under the truck, where it can pick up dirt and moisture. A stuck valve is the most common cause, with bad wiring and a plugged vent line close behind.

Commonly reported on: Silverado, Equinox, Malibu, Traverse.

Symptoms

Check engine light on
Faint fuel smell near the rear of the vehicle
Slow fuel filling or nozzle clicks off early
Normal driving and power

Common causes

most common: Vent valve stuck closed or failing
common: Faulty vent valve wiring or connector
common: Clogged vent line or canister filter
less common: Damaged charcoal canister

How to fix it

Fix	DIY?	Typical cost
Replace the vent valve	Yes	$60–180
Repair vent valve wiring or connector	Yes	$30–90
Have a shop test the vent circuit and replace the valve	Mechanic	$140–340
Replace the charcoal canister assembly	Mechanic	$280–550