P0446 minor

Evaporative Emission Control System Vent Control Circuit Malfunction

What does P0446 mean?

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.

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

  1. Locate the EVAP vent valve on or near the charcoal canister (usually near the fuel tank).

  2. Command the vent valve open and closed with a scan tool. Listen for a click each direction.

  3. Check vent valve resistance: typical spec is 22-36 ohms. Out of range means a failed solenoid.

  4. Inspect the canister vent filter: insects and debris can block it, causing backpressure.

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.

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