Evaporative Emission System Incorrect Purge Flow

What it means

The evaporative emission system stores fuel vapour in a charcoal canister and the purge valve meters it into the intake manifold while driving. P0441 means the control module commanded purge but did not see the expected response, either through the fuel tank pressure sensor, a purge flow sensor or a change in oxygen sensor and fuel trim behaviour. The flow may be absent, too low, or present when the valve should be closed.

Symptoms

• Check engine light with no obvious running problem
• Rough idle or stalling after refuelling if the purge valve is stuck open
• Faint fuel smell near the engine or rear of the car
• Hard starting after the car has sat in the sun
• Slightly elevated fuel consumption

Common causes

1. Purge valve stuck closed, stuck open or clogged with charcoal dust
2. Cracked, kinked or disconnected purge hose between canister, valve and intake
3. Saturated or broken charcoal canister releasing granules into the lines
4. Vent valve stuck closed so the canister cannot draw in air during purge
5. Fuel tank pressure sensor reading incorrectly
6. Wiring or connector fault at the purge valve giving an intermittent command

How to diagnose

1. Trace every EVAP hose from the canister to the purge valve and intake manifold, checking for cracks, collapsed sections and charcoal granules inside the lines
2. Unplug the purge valve and measure its coil: most read 20-40 ohm at 20 degrees C; an open or near-zero reading means the valve is faulty
3. Apply 12 V briefly to the valve and listen for a sharp click, then try blowing through it: it must be sealed when unpowered and flow freely when energised
4. Connect a hand vacuum pump to the purge valve outlet with the valve de-energised and pump to 15 inHg; the valve must hold vacuum for at least 60 seconds
5. Use the scan tool to command purge duty to 50-100 percent at idle and watch fuel tank pressure go slightly negative and short-term fuel trim shift; no change means no flow
6. Check the vent valve clicks and is open at rest, and inspect the canister for cracks and saturation from repeated overfilling

Terms to know

Related codes

Nearby codes in this group

• P0440Evaporative Emission System Malfunction
• P0442Evaporative Emission System Leak Detected (Small Leak)
• P0439Catalyst Heater Control Circuit
• P0443Evaporative Emission System Purge Control Valve Circuit
• P0438Catalyst Temperature Sensor High
• P0444Evaporative Emission System Purge Control Valve Circuit Open
• P0437Catalyst Temperature Sensor Low
• P0445Evaporative Emission System Purge Control Valve Circuit Shorted