Evaporative Emission Control System Malfunction
There's a problem with the evap system that controls fuel vapor emissions.
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 detects a leak or blockage in the system that captures fuel vapors from the tank instead of letting them escape into the air.
What the computer is actually seeing
The system monitors the EVAP lines, purge, and vent valves. It expects a certain pressure with no leaks during a testing cycle, typically measured at 0-5 inches of water column pressure.
What a healthy reading looks like
Pressure expected to be stable; no leaks should be detected during testing, which occurs at ambient temperatures during fuel system tests.
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. Check the gas cap. Ensure it's tight and seals properly. If it's cracked, replace it and clear the code.
- 22. Inspect EVAP hoses for cracks, breaks, or loose connections. Repair or replace as necessary. If hoses are good, continue.
- 33. Use a smoke machine to check for leaks in the EVAP system. Look for smoke escaping from hoses or the charcoal canister. If leaks are found, repair them.
- 44. Check the purge valve for proper operation. Apply voltage and ensure it opens. If it doesn’t, replace it.
- 55. Check the vent valve operation. It should open with a vacuum applied. If it's stuck or clogged, replace it.
Common causes
- Loose or defective gas cap
- Cracked or broken EVAP hoses
- Faulty purge or vent valve
- Leaking fuel tank
- Moisture in the EVAP canister
Typical repair cost
$$
Related codes
Frequently asked questions
Why do I get this code with a faulty gas cap?
Because a faulty or loose gas cap can cause a detectable leak in the EVAP system, which triggers this code.
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