P0440 Evaporative Emission System Malfunction
A general fault in the fuel-vapour system – a leak or a part that isn't working as expected.
Common causes
- Gas cap problem
- Faulty purge or vent valve
- Leak in hoses or canister
- Wiring fault
Symptoms
- Usually none besides the check engine light
Can I drive with it?
Safe to drive. Fix it before your next emissions test.
Tip: Look for a more specific EVAP code stored alongside it.
Which scanner reads it?
Any OBD2 scanner reads it.
Budget tools like the ANCEL AD310 read it; tools with live data and graphing – like the BlueDriver or OBDLink MX+ – help you find the cause. Not sure which fits you? Try the Find My Scanner quiz.
In the data
How common is it? At New York’s emissions inspections in 2020–21, P0440 was the #15 code found on cars that failed – 1.4% of all the codes found.
Of the vehicle complaints owners filed with NHTSA from 2015 to 2025, 10 quote P0440 – most often from Jeep, Toyota, Chrysler owners. Complaints lean toward serious problems, so treat this as a sign of how often the code turns up in real reports, not how often cars get it.
Both sources are compared on the Trends page.
Related codes
General information to help you understand a code – not a diagnosis. Your car’s service information or a qualified mechanic has the final word. See how we research.