What does it mean?
This fault says the refueling vapor control valve is not sealing when it should be closed, so the fuel tank stays connected to the canister at times the module wants it isolated. On sealed tank systems the module regularly checks that the tank can build and hold pressure or vacuum; if pressure bleeds away immediately, or the tank never develops the expected reading during a self test, the module decides the valve is stuck in its open position. Electrically the valve may test perfectly, which is why this is a performance code rather than a circuit code. A permanently open path means the canister receives vapour continuously and saturates, and the tank loses the pressure management that hybrid and sealed systems rely on.
Symptoms
- MIL (check engine lamp) on with evaporative pressure or leak codes stored
- Fuel odour that becomes stronger in warm weather or after filling the tank
- Tank pressure readings in live data that will not build or fall as the self test requires
- Repeated nozzle shut off or slow filling as the canister runs saturated
- Evaporative monitor that runs and fails rather than never completing
Likely causes
- Debris or charcoal dust on the valve seat preventing full closure
- Worn, swollen or hardened internal seal inside the valve
- Solenoid plunger sticking open because of contamination or corrosion
- Broken or weak internal return spring
- Mechanical damage to the valve body or a cracked housing allowing bypass flow
- Cracked or split vapour hose next to the valve giving the same test result
- Valve fitted the wrong way round or the wrong part number installed at a previous repair
How to fix it
- Check first that there is no electrical code holding the valve energised, since that mimics a stuck open valve
- Watch the tank pressure sensor in live data through a full seal and vent sequence to see where the pressure escapes
- Remove the valve and bench test it with low pressure air, de energised and energised, to prove it seals when closed
- Inspect the seat and inlet for charcoal dust and debris, and check the canister for internal breakdown if dust is found
- Examine the vapour hoses at the valve for cracks, splits and loose clamps that would give the same symptom
- Confirm the correct part and orientation before condemning anything else in the system
- Replace the valve, clear the codes and repeat the evaporative test to verify the tank now holds