OBD-II code · Powertrain (generic)
P0440 Evaporative Emission Control System Malfunction
A general fault in the evaporative emission (EVAP) system has been detected. The system seals the fuel tank and captures fuel vapour in a charcoal canister; this code indicates a failed leak test or sensor without identifying the specific failure.
Is it safe to drive with P0440?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyFuel filler cap loose or worn
- PossiblePurge valve stuck open or closed
- PossibleCracked EVAP hose
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.2–2.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Evap Canister, Evap Purge Valve, Fuel Filler Cap, Evap Vent Valve
Related codes
- P043DCatalyst Temperature Sensor Circuit High (Bank 2 Sensor 2)
- P043EEVAP System Leak Detection Reference Orifice Low Flow
- P043FEVAP System Leak Detection Reference Orifice High Flow
- P0441Evaporative Emission System Incorrect Purge Flow
- P0442Evaporative Emission System Leak Detected (Small Leak)
- P0443Evaporative Emission System Purge Control Valve Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.