Evaporative Emission System Leak Detected (Small Leak)
Indicates a small leak in the evaporative emission control 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 computer has found a small leak somewhere in the vapor lines or gas tank that lets fuel vapors escape.
What the computer is actually seeing
The onboard computer monitors pressure changes in the evaporative system. If it detects insufficient vacuum or pressure, it triggers this code.
What a healthy reading looks like
The expected pressure in the EVAP system is typically between 0-3 inches of H2O while performing the leak test, with a vacuum of at least 0.5 inches of H2O.
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. Start by checking the gas cap. Ensure it’s tightly sealed and not cracked. Re-test if needed.
- 22. Inspect the EVAP hoses for cracks or disconnections. Replace any damaged hoses found.
- 33. Perform a smoke test on the EVAP system to identify the leak source. Determine if there is visible smoke.
- 44. Check the purge valve for proper operation; it should open and close with engine vacuum.
- 55. Verify the fuel tank pressure sensor reading with a scan tool. Replace if readings are outside of normal range.
Common causes
- Loose or damaged gas cap
- Cracked or broken EVAP hoses
- Faulty purge valve
- Defective fuel tank pressure sensor
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but it's advisable to fix it soon to avoid emissions issues.
Will the code return after clearing it?
If the leak persists, it will likely return after a few drive cycles.
Why does this code sometimes appear with others?
It often pairs with faults related to the fuel system or other EVAP codes.
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