An EVAP leak is about a fault in the evaporative emission control system (EVAP). The EVAP’s job is to keep gasoline fumes in the fuel tank from getting to the atmosphere. This reduces air pollution and keeps the smell of fuel from reaching the inside of your car.
Fuel vapors are emitted from cars any time there is gasoline in the tank. So if you have a leak, even if you are not driving the car, those vapors are polluting the air 24 hours a day. Uncontrolled emissions like this account for about 20 percent of the stated pollution produced by cars. 3 signs that will let you know that there is a problem with the EVAP system:
- Check Engine Light Comes on The check engine light turns on while driving. This check engine light happens for many reasons, one being an EVAP leak. A slight fuel odor may equally be noticed, but it does not occur in all vehicles. If your Check Engine Light does come on, and you just filled up your gas tank, check the gas cap to see if it’s loose.
- A Loose Gas Cap. The most regular cause of an EVAP leak warning, or the Check Engine Light, is the gas cap not being closed correctly. If the cap is not fully tightened or closed all the way, the Check Engine Light may come on. Before taking your car to a mechanic, check your gas cap to make sure it is positioned on the filler correctly and closed tightly. It being open potentially leaves room for fuel to leak out of the vehicle.
- Leak in the Fuel System. If the gas cap is fitted on correctly, there may be a more serious issue, such as a leak in the fuel system. Other problems could be a faulty vent o-ring seal, defective leak detection pump, defective purge valve, or another small leak somewhere in the EVAP system.
While it could be safe to drive with an EVAP leak, you should get the leak fixed right away. EVAP issues can be challenging and the mechanic will have to use advanced troubleshooting techniques to know where the leak is, as well as how grave it is.