My cars check engine light came on yesterday I was going to go to my mechanic to get it checked out today. But before I could do that I had to get some gas. After I put in gas the light came off. I was happy, but didn't know why it did this. Anyone know about this?

 

Most likely the gas cap wasn't on tight, this will throw a cel.

 

gas cap.

 

As said above ! If the gas cap isn't properly tightened the system will detect a small leak in the evap emissions control system. Which will then trigger a check engine light. When you put gas in and tightened up the cap it stopped the leak and therefor fixed your problem !

 

Like everyone else stated. I have an issue with my cap where I can turn it, it'll click 3 times (or 20 for that matter) and its still not tight. What I have to do it hold the cap by the edge of its circumference and turn. A few others have this issue and found it to work as well.

 

This!

Happened to me first time I got gas in the S. the cap will "click" well before it's actually screwed down tight!

 

ahh the old Gas cap trick bit ya.....