P0446: Evaporative Emission Control System Vent Control Circuit Malfunction
Key takeaways
- P0446 points at the EVAP vent valve: the small valve that lets the fuel-vapor canister breathe, and that the computer closes to leak-test the system.
- It's an emissions fault, not an engine fault, so the car is safe to drive, but it will fail an OBD emissions inspection.
- The usual fix is a vent valve ($120–$350) or its wiring ($100–$250); a blocked vent filter or a charcoal canister ($300–$800) is next.
- On several 2019–2023 GM trucks, a manufacturer bulletin names dust getting into the evaporative canister as the cause.
- Some cars also set P0446 with a bad gas cap seal, so check the cap before paying for anything.
What P0446 means
The valve that lets your fuel-vapor canister breathe isn’t doing what the computer tells it to. The scanner name is Evaporative Emission Control System Vent Control Circuit Malfunction. The vent valve sits between the charcoal canister and fresh air. It stays open most of the time so the tank can breathe, and the engine computer closes it to seal the system for a leak test. P0446 sets when the computer sees a problem in the valve’s electrical circuit, or when tank pressure doesn’t respond the way it should when the valve is commanded open or closed. Exact test logic varies by make.
Is it safe to drive?
Yes. A vent fault doesn’t change how the engine runs. You’ll fail an OBD emissions inspection with the light on, and if the valve is stuck closed you may notice the pump nozzle clicking off early at every fill-up. The thing that changes the answer is a strong raw-gas smell around the car or in the cabin. That’s a sign of a real fuel leak, not a vent problem, and it needs a look before you keep driving. See car smells like gas.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Vent valve failed (stuck or burned-out coil) | Scan tool command doesn’t click the valve or change tank pressure; coil resistance out of spec | $120–$350 |
| Wiring or connector at the valve | Corroded or broken connector near the tank; no power or ground at the valve | $100–$250 |
| Blown fuse for the EVAP circuit | Fuse check; valve has no power at all | $0–$20 |
| Vent filter or hose blocked by dirt, mud or insects | Hose off the valve shows debris; valve works on the bench | $50–$200 |
| Charcoal canister packed with dust or damaged | Canister blocked or cracked; dirt in the valve; bulletin for your model | $300–$800 |
| Gas cap not sealing (some makes) | Cracked seal, cap doesn’t click | $15–$40 |
What to check first
- The gas cap. Tighten it until it clicks and look at the seal. It’s rarely the whole story on P0446, but it costs nothing to check. Our loose gas cap guide covers it.
- The EVAP fuse. Find it in the owner’s manual fuse chart. A blown fuse is the cheapest answer, but find out why it blew before driving off.
- Look at the valve. It’s usually near the tank or canister, under the rear of the car. Look for a cracked connector, green corrosion, or a vent hose packed with mud.
- Command the valve. A shop with a bidirectional scan tool can click the valve open and closed and watch tank pressure. This test separates the valve from the wiring in a few minutes.
- Clear it and drive. If you fixed a connector or cap, clear the code and drive normally for a few days. EVAP tests only run under certain conditions, so give it time.
- Check bulletins. GM has bulletins naming P0446. One covers 2019–2023 Silverado and Sierra pickups with dust getting into the evaporative canister; another gives a repair procedure for 2016–2019 Cruze. On those trucks, ask about the bulletin fix before replacing only the valve.
What it costs
The cheap outcome is a fuse, a cap, or a cleaned-out vent hose, under $60 in parts. The common outcome is a vent valve or its connector, $100–$350 at an independent shop. The expensive outcome is a charcoal canister at $300–$800, usually when dirt has packed it and ruined the valve too. Paying for a quick valve command test first keeps you from buying a canister you don’t need, or a valve that fails again because the canister behind it is full of dust.
Related codes
P0446 often travels with P0449 (vent valve solenoid circuit) and with leak codes like P0442 and P0455, because a valve that won’t close makes the system look leaky. P0440 is the general EVAP fault. If you’re not sure which to chase first, ask our AI mechanic with the full list of codes.
What owners report to NHTSA
27 complaints filed with NHTSA mention P0446, 12 of them since 2015, across 16 different models. The component owners most often filed it under: fuel system, gasoline.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| TOYOTA COROLLA | 7 | 1999, 2001, 2003 |
| TOYOTA CAMRY | 4 | 1998, 2000, 2001, 2002 |
Manufacturer service bulletins that name P0446
28 technical service bulletins and manufacturer communications filed with NHTSA mention P0446, from 5 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- GMC SIERRA 2500 (2020, 2021, 2022, 2023), bulletin 11010573: This technical bulletin provides repair information to correct a customer concern of Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister.
- CHEVROLET SILVERADO 3500 (2020, 2021, 2022, 2023), bulletin 11010573: This technical bulletin provides repair information to correct a customer concern of Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister.
- GMC SIERRA 3500 (2020, 2021, 2022, 2023), bulletin 10239087: This technical bulletin provides repair information to correct a customer concern of Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister.
- CHEVROLET SILVERADO 1500 (2019, 2020, 2021, 2022), bulletin 10244171: This technical bulletin provides repair information to correct a customer concern of Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister.
- GMC SIERRA 1500 (2019, 2020, 2021, 2022), bulletin 10251357: This technical bulletin provides repair information to correct a customer concern of Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister.
- CHEVROLET CRUZE (2016, 2017, 2018, 2019), bulletin 10172776: This technical bulletin provides a procedure to correct a condition of an MIL Illuminated with DTC P0446 Set.
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
What is the EVAP vent valve?
It's an electric valve, usually near the fuel tank or the charcoal canister, that lets fresh air in and out of the canister. The computer closes it to seal the system for a leak test. If it can't open or close when told to, P0446 sets.
Can I drive with P0446?
Yes. The engine runs the same. The downsides are a failed OBD emissions inspection and, if the valve is stuck closed, a tank that can be hard to fill because air can't escape.
Can a gas cap cause P0446?
On some cars, yes, because the computer can't seal the system for its test. It's not the most common cause, but at $15–$40 it's the cheapest thing to rule out.
How much does it cost to fix P0446?
Usually $120–$350 for a vent valve at an independent shop, or $100–$250 for a wiring repair. A charcoal canister job runs $300–$800. A blown fuse is the cheapest outcome at under $20.
Why is my gas pump clicking off with P0446?
A vent valve stuck closed or a canister blocked with dirt keeps air from leaving the tank as you fill it, so the pump nozzle shuts off early. That's a strong hint the vent side is the problem.