All fault codes

P0440: Evaporative Emission (EVAP) Control System Malfunction

LowPowertrainEmissions

Symptoms

  • Check engine light
  • Faint fuel smell, especially after refueling
  • No impact on driving

Common causes

  • Loose, damaged, or wrong-type fuel cap
  • Cracked or disconnected EVAP hose
  • Faulty purge or vent valve
  • Cracked charcoal canister
  • Leaking O-ring at fuel filler neck

What to do?

Start by tightening or replacing the fuel cap and clearing the code - this resolves a large share of P0440 cases. If the code returns, have the EVAP system smoke tested, since most leaks are too small to find by sight or sound.