Trouble code · Powertrain · Generic (all makes)

P0446 Evaporative Emission System Vent Control Circuit

There's a problem with the EVAP vent valve, which opens and closes so the system can test itself for leaks and let the tank breathe.

Safe to drive?
Usually OK to drive
Get it checked soon
Scanner you need
Any OBD2 scanner
Even a basic code reader shows it
NHTSA complaints quoting it
12
Vehicle complaints, 2015–2025

Common causes

  • Faulty vent valve (solenoid)
  • Vent valve or filter clogged with dirt or spider webs
  • Damaged wiring or connector
  • Faulty charcoal canister

Symptoms

  • Usually just the check engine light
  • Sometimes trouble filling the tank (the pump keeps clicking off)

Can I drive with it?

Safe to drive. Fix it before an emissions test.

Tip: The vent valve usually sits near the fuel tank or spare tire, where road dirt gets in – cleaning or replacing it is often the whole fix.

Which scanner reads it?

Any OBD2 scanner reads it. Bidirectional tools can command the vent valve closed to test it.

Budget tools like the ANCEL AD310 read it; tools with live data and graphing – like the BlueDriver or OBDLink MX+ – help you find the cause. Not sure which fits you? Try the Find My Scanner quiz.

In the data

How common is it? At New York’s emissions inspections in 2020–21, P0446 was the #11 code found on cars that failed – 1.6% of all the codes found.

Of the vehicle complaints owners filed with NHTSA from 2015 to 2025, 12 quote P0446 – most often from Toyota, Pontiac, Mazda owners. Complaints lean toward serious problems, so treat this as a sign of how often the code turns up in real reports, not how often cars get it.

Both sources are compared on the Trends page.

General information to help you understand a code – not a diagnosis. Your car’s service information or a qualified mechanic has the final word. See how we research.