Error code

OBD2 P0446

OBD2P0446
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Evaporative Emission System Vent Control Circuit.

Severity

moderateCan drive, but reduced performance and fuel economy may be noticeable.

Summary

P0446 indicates an issue with the evaporative emission system's vent control circuit malfunctioning, which is part of the EVAP system that manages fuel vapors.

Symptoms

  • Malfunction indicator light (MIL) illuminated
  • Slightly reduced engine performance and fuel economy

Common Causes

  • Loose or improperly installed gas cap
  • Improperly vented aftermarket gas cap
  • Damaged EVAP system components (tubes, hoses, gasket)
  • Clogged or blocked vent hose due to dusty environments
  • Spider nests blocking the vent line

Diagnosis

  1. Check all EVAP hoses for proper connection and condition
  2. Inspect wire harnesses for damage or corrosion
  3. Verify gas cap is properly seated with one or three clicks
  4. Test vent control valve using a vacuum pump to check for leaks
  5. Measure resistance at the vent control valve

Fixes

  • Replace damaged EVAP system components
  • Install an OEM gas cap if aftermarket one is improperly vented

FAQ

What should I do if the P0446 code appears after refueling?

Ensure the gas cap is properly tightened and try clearing the codes to see if they return.

How can I prevent this issue from recurring?

Regularly check and maintain all EVAP system components, including hoses, valves, and the charcoal canister.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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