I had a check engine light when I first bought the car, and that was just because of the fact that there was no air temp sensor. I fixed that and the check engine light never came back on. Not too long ago, thecar overheated, and my uncle says I need a new thermostat because of that. Could this also cause my check engine light to come back on?

That is my problem...my light is back on, and I don't know why.

 

Pretty sure an oveheated engine means you need to check it!

Read my other post to you and you'll be well on your way to asking questions that the experianced knolagable guys here on the forum will answer...

 

If you check to see what code(s) are stored, that will tell you why the service engine light is on. Then there is no guessing back and forth