P0440
Low SeverityEVAP System Malfunction
EVAP System
What Does P0440 Mean?
General EVAP system fault — the system that captures fuel vapors is not working properly.
Common Fix
Replace gas cap
Estimated Cost (DIY)
$5 - $15
Symptoms
- ⚠️Check engine light
- ⚠️Faint fuel smell possible
- ⚠️Failed emissions test
Common Causes
Loose or cracked gas caplikely
EVAP canister purge valve faultpossible
EVAP vent valve faultpossible
Cracked EVAP hosepossible
How to Diagnose P0440
- 1Tighten gas cap and clear code
- 2If code returns, inspect gas cap seal
- 3Check purge and vent valves
- 4Smoke test EVAP system
Need to read or clear this code?
Shop OBD2 Scanners on Amazon →Frequently Asked Questions
- What is the EVAP system?
- The EVAP system captures fuel vapors from the tank and routes them to the engine to be burned, preventing pollution.
- Can a loose gas cap cause P0440?
- Yes — the #1 cause of EVAP codes is a loose, cracked, or missing gas cap. Tighten it and clear the code.