5
votes
3answers
31k views

How important is a fuel cap?

I lost my fuel cap a couple months ago and haven't bothered finding a replacement. I haven't noticed any issues with it, but I'm wondering whether it's causing any damage or reducing gas mileage or ...
9
votes
2answers
7k views

Why would a new gas cap cause the “check engine” light to shut off?

This happened to a friend of mine: The "check engine" light came on in his truck (Toyota). He replaced the gas cap and the light shut off. Then I also had a "check engine" light come on in my 1994 ...