Evaporative Emission System Vent Valve Control Circuit High

Possible causes

• CommonFailed vent valve or solenoid
• CommonCorroded connector - the vent valve is usually mounted under the vehicle
• CommonVent filter blocked with dirt, or an insect nest in it
• CommonDamaged wiring under the vehicle
• PossibleDebris from a degraded charcoal canister jamming the valve
• RareFailed control module driver

What you might notice

• Check engine light on
• Failed emissions test
• Hissing when the fuel cap is opened
• Fuel tank sounding pressurised
• Difficulty filling the tank - the pump cutting off repeatedly
• Usually no drivability symptom

What to check, in order

1. Disconnect the valve and check whether the high reading persists at the harness.
2. Inspect the vent valve and its filter underneath the vehicle. Corrosion and blockage are the two common causes, and insect nests in the vent filter are a genuine and frequent one.
3. Check the connector for corrosion and water - this valve takes constant road spray.
4. Measure the valve winding resistance against specification.
5. Check whether the valve opens and closes when commanded.
6. Note that EVAP monitors only run in particular conditions of fuel level and temperature, so confirming a repair can take several journeys.