I was on my way to work which is about 15 minutes away and I noticed that my gas gauge was dropping more than it usually would. I was a little under a full tank and I ended up with 3/4 by the time I got to work and about half way to work my check engine light came on. What could do this?

 

If the CEL came on the first thing you need to do is read the codes. Unless you are in California most parts stores do it free, or you can buy a code reader on Amazon for 20 bucks. Post the number code, not what the Autozone flunky says it means.

Also post which engine you have.