EmissionsSeverity Low: usually safe to drive

P0440Evaporative Emission System

What it means

The ECU sees a problem in the evaporative emission (EVAP) system, which stores fuel vapour in a charcoal canister and burns it in the engine.

Symptoms

Check engine light
Possibly a fuel smell
Usually no change in how the car drives

Common causes

Leak in the EVAP system (hoses, filler neck, canister)
Faulty purge or vent valve
Loose or faulty fuel cap

What to check first

Check the fuel cap seal
Smoke-test the EVAP system
Run the purge and vent valve tests

Can I drive with P0440? Usually yes. P0440 rarely affects how the car drives, but it keeps the check engine light on and can fail an emissions test.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

Cases with P0440 (0)

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P0440: questions and answers

What does P0440 mean?

P0440: Evaporative Emission System. The ECU sees a problem in the evaporative emission (EVAP) system, which stores fuel vapour in a charcoal canister and burns it in the engine.

What are the symptoms of P0440?

Check engine light. Possibly a fuel smell. Usually no change in how the car drives.

What causes P0440?

Leak in the EVAP system (hoses, filler neck, canister). Faulty purge or vent valve. Loose or faulty fuel cap.

How do you diagnose P0440?

1. Check the fuel cap seal 2. Smoke-test the EVAP system 3. Run the purge and vent valve tests

Can I drive with P0440?

Usually yes. P0440 rarely affects how the car drives, but it keeps the check engine light on and can fail an emissions test.