Evaporative Emission Control System Vent Control Circuit Malfunction
The P0446 code means the vehicle's onboard diagnostic system has detected: Evaporative Emission Control System Vent Control Circuit Malfunction. This is a minor severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $30-$150 for the vent solenoid part alone (DIY); roughly $200-$500 done at a shop; a full charcoal canister replacement is the expensive case at about $450-$650 parts and labor
A cracked or loose gas cap causes 60%+ of EVAP codes. This $8 replacement clears P0442, P0455, and P0457 more often than any other repair.
If a new gas cap does not clear it, the leak is somewhere in the EVAP plumbing. A smoke machine finds the exact leak -- a cracked hose, bad seal, or stuck vent valve -- in minutes instead of guessing at parts.
Clear the code after the repair. If the light stays off after 50 miles, you just saved $200+ in shop fees.
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Common Symptoms
- Check Engine Light on
- No drivability problems
- Possible fuel odor
Probable Causes (Ranked by Likelihood)
- Faulty or stuck EVAP vent valve (canister vent solenoid) Very High
- Blocked vent filter on canister Moderate
- Wiring issue to vent solenoid (open or short) Moderate
- Charcoal canister damage Low
Common Fixes by Vehicle
What techs usually find when diagnosing P0446 on specific vehicles — tap your vehicle for the fix and the exact part:
2005-2017 Toyota Camry/Corolla moderate DIY
EVAP vent control valve (canister close valve) failure. The valve is located near the charcoal canister under the vehicle. Toyota part 90910-12276. Test by applying 12V to the valve -- it should click and hold vacuum. Spider webs and dirt clog the vent filter -- clean or replace the filter first before condemning the valve.
Labor: 30-45 min2007-2019 Chevrolet Silverado/Tahoe 5.3L easy DIY
EVAP vent solenoid failure is common on GM trucks. The solenoid is mounted near the charcoal canister behind the rear axle. ACDelco. The vent filter also clogs with dirt -- clean the filter mesh before replacing the solenoid. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30 min2005-2015 Nissan Altima/Frontier 2.5L/4.0L moderate DIY
The EVAP canister vent control valve sticks closed on Nissan vehicles. Located near the fuel tank on the driver side. Replace with an OE-quality Dorman unit. Before replacing, check for kinked or crushed EVAP vent hoses near the charcoal canister. Road debris commonly damages the hoses on trucks. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30-45 min2010-2018 Ford F-150/Explorer 3.5L/5.0L easy DIY
The EVAP canister purge valve (Motorcraft) sticks open, which can also set P0446. Located on the intake manifold area, easily accessible. Test the valve by applying vacuum with a hand pump -- it should hold vacuum when powered and release when not powered. Also check the canister vent solenoid on the charcoal canister. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 20 minFrequently Asked Questions
Where is the EVAP vent valve located?
On most vehicles it is mounted on or near the charcoal canister, which is typically located near the rear of the vehicle close to the fuel tank. On some Toyota and Lexus models it sits on the canister itself.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Locate the EVAP vent valve on or near the charcoal canister (usually near the fuel tank).
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Command the vent valve open and closed with a scan tool. Listen for a click each direction.
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Check vent valve resistance: typical spec is 22-36 ohms. Out of range means a failed solenoid.
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Inspect the canister vent filter: insects and debris can block it, causing backpressure.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- Toyota Camry, Tundra, and 4Runner
- Lexus RX300 and ES300
- Chevrolet Silverado
- GMC Sierra
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