P0440 Evaporative Emission System
What does P0440 mean?
P0440 — Evaporative Emission System. This is an OBD-II diagnostic trouble code a scanner retrieves when your vehicle's computer detects evaporative emission system. The level of risk depends on how the vehicle is currently running and how long you've been driving with the light on.
Common causes of P0440
- Fuel cap loose or sealing poorly
- Small leak in EVAP lines or canister
- Faulty purge or vent valve
- Leaking fuel tank or filler neck seal
- Cracked charcoal canister
How to fix P0440
- Tighten or replace the fuel cap and clear the code first
- Smoke-test the EVAP system at tank, canister, and vent
- Command the purge and vent valves with a scan tool
- Inspect EVAP lines and the canister for cracks
- Repair the identified leak and run a full EVAP monitor cycle