Hoping to be pointed in the right direction here. I recently replaced my air filter with a Fram CA9409 filter. This is the first time I replaced an air filter on my own. A few days after replacement my check engine light went on. It kept turning off and on every few days for 2 weeks or so. Finally took to Midas and one of the guys said the filter cover wasn't installed properly so he fixed it. He said I probably have a bad air sensor if it comes back on. CEL stayed off for 2 days and then came back on and now it's on permanently. I recently got my safety instepection and the light was off after I got the car back (I assume CEL was reset during the insepction). Unfortunatly I don't know the actual fault code. Any ideas before I take to the mechanic? Car drives fine as far as I can tell.

Thanks
2007 A4 Turbo

 

Wait and see if it comes back on. If so take it to Autozone and have them pull the codes. That should help narrow down the problem.

 

This. You can't tell much without the code. It could be a myriad of things.