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P0446 — EVAP Vent Control Circuit Fault

P0446 is set when the engine control module detects that the EVAP vent valve circuit is not behaving as commanded. The vent valve is the normally-open solenoid that lets the charcoal canister breathe — and closes during the EVAP leak test to seal the system. P0446 typically means the vent valve is stuck (mechanically or electrically) so that the system can never seal properly for the leak test.

P0446 means evap vent control circuit fault. A vehicle usually stays drivable short-term with this code, but it should be diagnosed promptly. The most common cause is failed evap vent valve / vent solenoid (mechanical sticking) (typically $80–$350). Causes and cost vary by make and model; confirm the root cause before replacing parts.

Severity: low powertrain Safe to drive (short term)

Reviewed by MECH AI Editorial · Last verified

What does P0446 mean?

P0446 is set when the engine control module detects that the EVAP vent valve circuit is not behaving as commanded. The vent valve is the normally-open solenoid that lets the charcoal canister breathe — and closes during the EVAP leak test to seal the system. P0446 typically means the vent valve is stuck (mechanically or electrically) so that the system can never seal properly for the leak test.

What are the symptoms of P0446?

What causes P0446?

Cause Likelihood Estimated repair (USD)
Failed EVAP vent valve / vent solenoid (mechanical sticking) Most common $80–$350
Dirt, debris, or spider webs clogging the vent valve filter — Common on trucks and SUVs with the canister mounted under the vehicle. Common $20–$100
Damaged wiring or connector at the vent valve Common $50–$250
Failed PCM driver circuit for the vent valve (rare) Rare $400–$1,500
Cracked or saturated EVAP charcoal canister Occasional $200–$600

Repair costs are typical US ranges and vary by make, model, model year, and labor rate. A diagnostic trouble code is a symptom, not a guaranteed failed part — confirm the root cause before replacing anything.

Is it safe to drive with P0446?

In most cases a vehicle stays drivable for short trips with P0446 active, but you should diagnose and repair it promptly. This is a low-severity code — ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on your specific make and model.

How to diagnose P0446

  1. Locate the vent valve on this vehicle

    The vent valve is mounted on or next to the charcoal canister. On most modern trucks and SUVs that is behind the rear bumper or near the fuel tank. On many cars it sits in the engine compartment. Consult the service manual for the exact location.

    Tools: Vehicle-specific service information

  2. Test the vent valve electrically

    Disconnect the valve connector. With the key on, check for battery voltage on the power side. Apply 12 V across the solenoid terminals directly — you should hear and feel it click. A solenoid that does not click is dead and needs replacement.

    Tools: Multimeter, Test leads / jumper wires

  3. Test the vent valve mechanically

    Disconnect the hose at the vent valve. Connect a hand vacuum pump. With the solenoid de-energized, the valve should let air flow freely (no vacuum holds). With 12 V applied, the valve should hold vacuum. A valve that holds vacuum at rest, or that leaks vacuum when commanded closed, is the problem.

    Tools: Hand vacuum pump, 12 V test source

  4. Inspect for contamination

    Trucks and SUVs frequently get spider webs, mud, or sand inside the vent valve filter on the canister side. Some vehicles have a dust filter that is replaceable; others integrate it into the valve assembly. Clean or replace as needed.

    Tools: Compressed air, Replacement filter (if applicable)

  5. Confirm the canister itself is intact

    With the vent valve removed, look into the canister port for cracked plastic, saturated charcoal (will smell strongly of fuel), or debris. A failed canister will cause repeated P0446 set events even after the vent valve is replaced.

    Tools: Flashlight

How do I fix P0446?

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P0446: frequently asked questions

What does diagnostic trouble code P0446 mean?

P0446 is set when the engine control module detects that the EVAP vent valve circuit is not behaving as commanded. The vent valve is the normally-open solenoid that lets the charcoal canister breathe — and closes during the EVAP leak test to seal the system. P0446 typically means the vent valve is stuck (mechanically or electrically) so that the system can never seal properly for the leak test.

What are the symptoms of P0446?

Check Engine Light is illuminated. Difficulty filling the fuel tank (pump clicks off repeatedly). No other drivability problems. Vehicle will fail emissions / smog testing. Sometimes accompanied by P0455 (large leak) on the same scan

What causes P0446?

Failed EVAP vent valve / vent solenoid (mechanical sticking) (most-common). Dirt, debris, or spider webs clogging the vent valve filter (common). Damaged wiring or connector at the vent valve (common). Failed PCM driver circuit for the vent valve (rare) (rare). Cracked or saturated EVAP charcoal canister (occasional)

Is it safe to drive with P0446?

In most cases a vehicle stays drivable for short trips with P0446 active, but it should be diagnosed and repaired promptly — this is a low-severity code. Ignoring it can lead to further damage or a failed emissions test. Specific tolerance varies by make and model.