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P0440

Evaporative emission control system malfunction

The ECU has detected a general malfunction in the EVAP system that stores and controls fuel vapours.

What this code means

The ECU has detected a general malfunction in the EVAP system that stores and controls fuel vapours.

Possible causes

  • Loose or damaged fuel cap
  • Leaking EVAP hose
  • Faulty purge or vent valve
  • Charcoal canister problem
  • Wiring fault

Common symptoms

  • Check engine light
  • Usually no driveability change
  • Possible fuel-vapour smell

Checks to make

  1. Check fuel cap condition and sealing
  2. Inspect accessible EVAP hoses
  3. Check purge and vent operation
  4. Smoke-test the system if required

Safety

  • Do not replace parts from the code alone. Confirm the fault with live data, wiring checks and manufacturer procedures. Keep clear of hot or moving engine components.

Model notes

The code definition is generic; exact diagnostic thresholds, component locations and repair procedures vary by vehicle.