The EVAP system captures fuel vapor from the tank so it doesn't escape into the air, and periodically the computer runs a pressure test on it. This code means the system detected a leak large enough to fail that test — most often something as simple as a loose or missing fuel cap.
Symptoms
- Usually no drivability symptoms at all
- Sometimes a faint fuel smell near the fuel filler area
- Check engine light on, possibly clearing itself after a few drive cycles if the cause was a loose cap that's since been tightened
Likely causes
- Fuel cap loose, missing, or with a worn seal — the single most common cause by far
- A cracked or disconnected EVAP hose somewhere between the tank and the charcoal canister
- A failed purge or vent valve stuck open
- A cracked charcoal canister or a corroded fuel tank sending unit gasket
How to diagnose it
- Check and reseat the fuel cap first — tighten until it clicks, then clear the code and see if it returns after a few drive cycles
- Visually inspect all visible EVAP hoses (often running along the top of the fuel tank) for cracks or disconnection
- A smoke test at a workshop is the most reliable way to pinpoint a leak that isn't visible or obvious
Typical fixes & cost
- Replace the fuel cap15–40 EUR
- Repair or replace a cracked/disconnected EVAP hose60–200 EUR
- Replace a faulty purge or vent valve100–350 EUR
Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief