P04B4

  • Powertrain
  • Generic (SAE)
  • Emissions
SeveritySeverity level 3 of 5: Diagnose soon.

Diagnose soon

Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.

Standard definition

Refueling Vapor Control Valve Stuck Closed

This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.

In plain English

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

A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.

Can I keep driving?
Safe to drive
Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
Urgency
Diagnose soon
Will it pass emissions
No
Check engine light
Solid
Likely causes
#CauseHow oftenComponent
1Valve stuck closed due to seal or debrisVery common
2Carbon or debris buildup preventing free movementOccasional
3Component wear with age - mechanical playOccasional

Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.

Components involved
  • Refueling Vapor Valve
Sources
Definition
Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
Diagnostic guidance
Written and reviewed in-house. See our editorial policy.
Review status
Awaiting review

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