If the following situations occur, the fuel tank cap needs to be replaced:

1.Cap does not tighten properly
Most Fuel Tank Filler Cap/gas caps are designed to click once they are tightened sufficiently. If the cap does not click, or clicks and then pops loose again then that may be a sign that it may need to be replaced.

2.Fuel smell from the vehicle
If the Fuel Tank Filler Cap/gas cap seal becomes damaged or worn it may cause fuel vapors from the gas tank to leak from the filler neck. This may result in a gasoline odor from the vehicle as a result of the escaping vapors.

3.Check Engine Light comes on
A bad or failing fuel cap will not necessarily cause major performance issues, but it can set off the Check Engine Light, which will prevent the vehicle from passing an emissions test. If you suspect that your gas cap may be having an issue, please take a minute to check the gas