Evaporative Emission System Low Purge Flow

Possible causes

• CommonFailed purge control valve
• CommonCorroded connector or damaged wiring
• CommonSplit, perished or disconnected purge hose
• CommonValve stuck open by debris from a degraded charcoal canister
• PossibleBlown fuse on the circuit
• RareFailed control module driver
• CommonBlocked purge line or a canister blocked with fuel
• PossibleCanister overfilled with liquid fuel from repeated overfilling at the pump

What you might notice

• Check engine light on
• Failed emissions test
• Fuel smell in some cases
• Usually no drivability symptom

What to check, in order

1. Check the purge line from the canister to the engine for blockage and kinks.
2. Check the valve actually opens when commanded.
3. Ask whether the tank is habitually overfilled - clicking the pump repeatedly after it cuts off pushes liquid fuel into the charcoal canister, which blocks it and is a common cause.
4. Inspect the canister for damage and saturation.
5. Note whether the car is hard to start straight after refuelling. That symptom is close to diagnostic for a purge valve stuck open, and it costs nothing to observe.
6. Check the purge hoses for splits and disconnection.
7. Measure the valve winding resistance against specification.
8. Inspect the connector for corrosion.
9. Check whether the valve holds vacuum when closed. A valve that leaks with no power applied is stuck open, and that is what causes the hard starting.