P0446 minor

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.

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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

Try This First ($8 Fix)

Stant 10838 OE Fuel Cap

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.

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Find the Leak

THIKPO Automotive Smoke Machine

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.

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Clear the Code

ANCEL AD310 OBD-II Scanner

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

Step-by-Step Diagnostic Procedure

Locate the EVAP vent valve on or near the charcoal canister (usually near the fuel tank).
Command the vent valve open and closed with a scan tool. Listen for a click each direction.
Check vent valve resistance: typical spec is 22-36 ohms. Out of range means a failed solenoid.
Inspect the canister vent filter: insects and debris can block it, causing backpressure.

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 min

Common fix part Dorman EVAP Canister Vent Valve View on Amazon→ Compare fitment at PartsGeek→

2007-2019 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 214-2149. The vent filter also clogs with dirt -- clean the filter mesh before replacing the solenoid. GM TSB #07-06-04-030A covers EVAP vent circuit diagnosis.

Labor: 30 min

Common fix part ACDelco EVAP Vent Solenoid View on Amazon→ Compare fitment at PartsGeek→

2005-2015 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 Dorman 911-502. Before replacing, check for kinked or crushed EVAP vent hoses near the charcoal canister. Road debris commonly damages the hoses on trucks.

Labor: 30-45 min

Common fix part Dorman EVAP Canister Vent Valve View on Amazon→ Compare fitment at PartsGeek→

2010-2018 Ford F-150/Explorer 3.5L/5.0L easy DIY

The EVAP canister purge valve (Motorcraft CX-2536) 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.

Labor: 20 min

Common fix part Dorman EVAP Purge Valve View on Amazon→ Compare fitment at PartsGeek→

Frequently 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.