P0446 on Chevrolet: How to Diagnose & Fix
Evaporative Emission Control System Vent Control Circuit
2 Chevrolet models · 2 documented issues · $60-$450 repair
P0446 on Chevrolet by model: symptoms, diagnosis and fix
The vapor-canister purge solenoid on the V6 Equinox (and Terrain) commonly fails stuck-open, letting fuel vapor flow into the intake when it shouldn't. This sets DTC P0496 (EVAP flow during a non-purge condition) and sometimes P0455/P0446, illuminates the check-engine light, and can cause a rough/rich idle, hard starting, and even a faint fuel smell. It is one of the most frequently replaced emissions parts on the V6 Equinox because the valve is a known weak point and the repair is cheap and easy. The valve sits on top of the engine and is a roughly one-hour DIY job.
Common Symptoms
- Check-engine light with code P0496 (sometimes P0455/P0446)
- Rough or rich idle, occasional stumble
- Hard starting, especially right after refueling
- Faint raw-fuel smell
- Failed emissions/EVAP monitor readiness
How to Fix
Confirm P0496 and inspect the purge-valve vacuum lines for cracks and the connector for damage before replacing. Replace the vapor canister purge valve with the GM/ACDelco OE part 12690512 (supersedes 12610560). After replacement, clear codes and run a drive cycle to confirm the EVAP monitor passes and the light stays off. Also verify the gas cap and EVAP lines if leak codes (P0455/P0446) accompany the purge code.
Sources for this issue (1)
A very common GMT800 Silverado problem is contamination of the EVAP canister vent valve/solenoid by dust, road debris, or water intrusion. When the vent cannot flow properly, the truck sets EVAP leak or vent performance codes and may repeatedly shut off the gas pump during refueling. GM issued service bulletins and updated vent relocation kits for trucks used in dusty environments.
Common Symptoms
- check engine light
- fuel nozzle clicks off repeatedly while filling
- EVAP small or large leak codes
- failed emissions inspection
- intermittent fuel smell near rear of truck
How to Fix
Diagnosis includes smoke testing the EVAP system, commanding the vent valve with a scan tool, and inspecting the vent hose/filter for blockage. Repair usually involves replacing the vent solenoid and installing the updated relocated vent hose/filter kit to move the inlet away from road splash and dust. Clearing codes without updating the vent routing often leads to repeat failures.
Sources for this issue (1)
P0446 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0446 mean on a Chevrolet?
P0446 stands for "Evaporative Emission Control System Vent Control Circuit." This emissions code points to a problem in the evaporative emission (EVAP) system's vent control circuit, which manages the vent valve that lets the charcoal canister breathe and seals it during leak tests. The EVAP system captures fuel vapors from the tank to keep them out of the atmosphere, and the vent valve must open and close on command for the system to work and self-test. The code sets when the engine computer detects an electrical or performance fault with this vent valve or its circuit. It usually causes only a check engine light with no driveability change, but it does prevent proper EVAP leak monitoring. On Chevrolet it is documented across 2 models: Equinox, Silverado 1500.
What are the most common causes of P0446?
The most common causes of P0446 are: Faulty EVAP vent control valve (solenoid), Wiring or connector fault in the vent valve circuit, Vent valve clogged with dirt, debris, or spider webs, Damaged or corroded vent valve connector, Blocked or pinched vent hose or filter, Faulty charcoal canister assembly, Faulty engine control module driver circuit. The specific cause varies by vehicle.
How much does it cost to fix P0446 on a Chevrolet?
Published repair estimates on Chevrolet range from $60 to $450 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.