OBD-II · P0455
P0455 Code: Large EVAP System Leak Detected
Evaporative emission system leak detected (large leak)
The short version
Yes, safe to drive right away — it only affects vapor emissions, not engine performance or safety — but fix it soon to avoid fuel odor and pass emissions testing.
- Severity: Low
- Most common cause: Missing or improperly installed gas cap
- 5 diagnosis steps in order
- 4 symptoms tied to this code
Darker bars are the more common causes; bar length is the top expected repair cost. Start with the dark, cheap causes before the expensive ones.
Can I keep driving?
Yes, safe to drive right away — it only affects vapor emissions, not engine performance or safety — but fix it soon to avoid fuel odor and pass emissions testing.
Symptoms
- Noticeable fuel smell near the vehicle
- Solid check engine light
- Usually no effect on driving or performance
- Failing an emissions inspection if applicable
Causes & repair cost
Missing or improperly installed gas cap
Most common$5 – $25
Disconnected or clearly cracked EVAP hose
Most common$80 – $250
Purge or vent valve stuck open
Possible$100 – $300
Fuel tank or level sensor unit damage
Rare$300 – $800
Large leaks are usually easier to find than small ones, so cost is often low if it's just a cap or a disconnected hose; final cost depends on how accessible the EVAP components are on your specific model.
Estimate the repair for your carDiagnosis steps in order
- Verify the gas cap is present and properly seated
- Visually inspect all accessible EVAP hoses
- Use a smoke test to locate the source of the large leak
- Test purge/vent valves both electrically and mechanically
- Inspect the fuel tank and level sensor if leak persists
FAQ
Can I drive with a P0455 code?
Yes, completely safe — it doesn't affect vehicle performance or safety.
Why do I smell gas with this code?
Because fuel vapors are escaping from an open point instead of being contained by the system.
Does this code indicate a fire risk?
The leak is usually vapor, not liquid fuel, but it's still best fixed without long delay for safety and comfort.
What's the difference between this code and P0442?
This is a large, easier-to-find leak, while P0442 is a small leak that's harder to pinpoint.
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