P0455Powertrain
Powertrain · SAE
EVAP System Leak Detected (Large Leak)
Meaning
The ECU has detected a large leak in the evaporative emissions system. The EVAP circuit cannot hold the expected vacuum or pressure during the test.
Common causes
- Missing or very loose fuel cap
- Disconnected or clearly cracked EVAP hose
- Vent valve stuck in the open position
- Damaged canister or its connections
- Visibly broken EVAP component
Symptoms
- Check-engine light on
- Noticeable fuel smell
- Possible emissions-test failure
- Usually no significant effect on drivability
- Possible hard restart right after refuelling
Severity
Moderate: a substantial evaporative-emissions leak, but with no immediate mechanical risk.
What to do
- First confirm the fuel cap is present and correctly tightened
- Inspect the EVAP hoses for disconnected or broken sections
- Check that the vent valve is not stuck open
- Run a smoke test to pinpoint the leak precisely