Evaporative Emission System Leak Detected (Small Leak)
A small leak has been detected in the evaporative emissions system.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The car's computer found a tiny leak in the system that's supposed to keep fuel vapors from escaping into the air.
What the computer is actually seeing
The Engine Control Module (ECM) runs a self-test of the fuel vapor system; it looks for a change in pressure or vacuum that indicates a leak is present.
What a healthy reading looks like
Expected pressure values during testing should be stable at approximately 0.5-4.0 inches of H2O when the system is sealed tight.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Visually inspect the gas cap for cracks or wear. If damaged, replace it and clear the code. Decision: Did the light come back?
- 22. Check that the gas cap is tightened properly (clicks when closed). Decision: Did this fix the problem?
- 33. Scan for additional codes that may indicate broader issues with the EVAP system. Decision: Are there codes related to other EVAP components?
- 44. Inspect EVAP hoses for cracks or damage. If found, repair or replace them. Decision: Is there a noticeable leak?
- 55. Test the purge and vent valves for operation. Use a smoke machine if needed to detect leaks. Decision: Do valves function properly?
- 66. If all above checks are good, consider inspecting or replacing the charcoal canister.
Common causes
- Faulty gas cap not sealing properly
- Cracks or holes in hoses or lines
- Faulty purge or vent valves
- Loose or damaged fuel tank
- Defective charcoal canister
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but fix it soon to avoid emissions issues and potential check engine light reactivation.
Will this code come back after I clear it?
If the leak is not resolved, yes, the code will return.
Why does this code sometimes pair with other codes?
It often indicates a systemic issue in the EVAP system, which can cause multiple codes related to emissions.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →