* Check Engine Light (CEL): This is the most common symptom. The car's computer detects the leak and illuminates the CEL. The specific trouble code will pinpoint the area of the leak.
* Reduced fuel economy: Leaking fuel vapors mean you're losing fuel.
* Failure of emissions testing: A significant EVAP leak will cause the vehicle to fail an emissions test.
The leak could be in various components of the EVAP system, including:
* Gas cap: This is the most common culprit. A loose or damaged gas cap is a frequent cause of EVAP leaks.
* Gas tank: A crack or hole in the tank itself is less common but more serious.
* Fuel lines and hoses: These can become cracked, brittle, or disconnected over time.
* Purge valve: This valve controls the flow of fuel vapors to the engine. A malfunctioning valve can contribute to leaks.
* Canister: The canister stores the fuel vapors temporarily. Cracks or damage to the canister can cause leaks.
* Sensors: Various sensors monitor the system's pressure and operation; a faulty sensor can trigger a false EVAP code.
To fix the leak, a mechanic will need to diagnose the specific problem using a pressure test or smoke test to pinpoint the location of the leak. The repair could be as simple as replacing a gas cap or as complex as replacing a section of fuel line or the entire gas tank.
