P04B2Refueling Vapor Control Valve Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. Plug-in hybrids and range extenders with a sealed, pressurised tank have an electric valve in the vapour line between tank and canister. It is normally closed and opens before refuelling, so that the tank is depressurised – the filler flap is only released then – and refuelling vapour reaches the canister (Ford patent). P04B2 means the control wire is shorted to positive: the valve cannot be driven and does not open, the driver may switch off for protection. The tank cannot be depressurised before refuelling and refuelling vapour cannot reach the canister. No manufacturer document available to us uses this code – Ford reports its tank isolation valve as P2418/P2450 – so the description follows CARB and the component patent.
- What you may notice
- Check engine light on
- Filler flap does not open after pressing the refuel button, or only after a delay
- EVAP readiness not set
- Likely causes
- LikelyControl wire touching battery positive
- PossibleValve coil with shorted turns (driver overcurrent)
- PossibleCorrosion in the connector
- RareDriver in the control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.