i dont have a reader for this year car yet and the car is running fine but im lost to as what it could be. it went on a few weeks after the gmmg exhaust installation. and yes i did a quick search didnt turn up much. what do you guys think it most likely is? O2's?

 

Just go down to autozone they will read it for free. Once you find out what code is being thrown then you can start to figure out what you need to do. It can be anything, so you got to go get it read, then let us know.