P0446: Evaporative Emission System Vent Control Circuit Malfunction
System: EVAP (fuel vapor) systemThe valve that opens and closes the fuel vapor system's fresh air vent is not working or not reporting correctly.
Severity: 1 of 4
Generally safe to drive. This is an emissions fault and does not change how the engine runs. You may fail inspection. If the vent is stuck closed you may notice the pump nozzle clicking off early when you refuel. A strong raw fuel smell means find the source promptly.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0446 means
The EVAP vent valve sits between the charcoal canister and the outside air. It normally stays open so the fuel tank can breathe. During the leak self test the computer closes it to seal the system.
P0446 means the computer saw an electrical fault in the vent valve circuit, or on some vehicles that the system did not respond as expected when the vent was commanded closed or open.
The vent valve usually lives under the car near the fuel tank or canister, where dirt, water, and road salt can block it or corrode its connector.
Common causes (cheapest likely first)
- Failed vent valve (vent solenoid). The most common cause. They are exposed to dirt and water.
- Blocked vent or vent filter. Mud, dust, or insects can clog the fresh air side.
- Corroded connector or damaged wiring. Check the plug under the car for green corrosion or broken locks.
- Blown fuse or relay. Check the EVAP circuit fuse.
- Damaged charcoal canister. Overfilling the tank can push fuel into the canister and damage it.
Symptoms
- Check engine light
- Usually no drivability change
- Fuel pump nozzle shuts off early when refueling
- Failed emissions test
DIY difficulty: Easy to moderate
Vent valves are often a few bolts and one connector, though rust can make it slower. Check the fuse and connector before buying parts.
Tools: OBD-II scanner, Multimeter, Jack and jack stands, Basic hand tools, Contact cleaner
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Vent valve or solenoid | $25 to $150 | 0.3 to 1.5 h | $25 + 0.3 × $110 = $58 $150 + 1.5 × $190 = $435 |
| Wiring or connector repair | $5 to $40 | 0.5 to 1.5 h | $5 + 0.5 × $110 = $60 $40 + 1.5 × $190 = $325 |
| Charcoal canister | $80 to $400 | 0.8 to 2.0 h | $80 + 0.8 × $110 = $168 $400 + 2.0 × $190 = $780 |
Watch a repair video
Search YouTube for “P0446 fix” videos. Pick a recent video that matches your engine, and confirm the diagnosis before buying parts.
By make
This code works the same way on every make. See brand notes.
Repair manuals
Step-by-step service manuals with torque specs and wiring diagrams:
Haynes manuals Chilton manuals
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Related codes
Check for recalls
Before paying for a repair, enter your VIN in the NHTSA recall lookup. Emissions parts may also be covered by a federal emissions warranty; check your warranty booklet.
FAQ
Can a gas cap cause P0446?
Not usually. P0446 points at the vent valve circuit. A loose cap more often sets P0455 or P0457, though checking the cap is free.
Why is it hard to fill my tank?
A vent stuck closed or a blocked canister stops air from escaping as fuel goes in, so the nozzle clicks off. That fits with P0446.
Is P0446 expensive to fix?
Usually not. A vent valve is one of the cheaper EVAP parts. Canister replacement costs more.