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P04B4 Powertrain

Refueling Vapor Control Valve Stuck Closed

Same as P04B3 with the valve stuck closed - vapor cannot reach the canister during refueling, vapor escape from the filler is possible.

Affected components

  • Refueling vapor valve

Common causes

  • High likelihood: Valve stuck closed due to seal or debris
  • Low likelihood: Carbon or debris buildup preventing free movement
  • Low likelihood: Component wear with age - mechanical play

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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