So recently my CEL came on and when I went to have codes pulled, the guy said that something was already plugged into my OBD2 port. I know the previous owner of the car mentioned that he installed some sort of "chip" to help the high idle that these engines are supposedly notorious for. Could this be what we are seeing on my OBD2 port? If so, how would one remove it safely in order to check the code triggering the CEL. I will say that my exhaust is rattling against the frame because the rear tires are so wide that there isn't much room for the pipes (according to my exhaust guy) so I'm wondering if an 02 sensor has shaken loose slightly? The engine runs just as good as it ever has and there is no obvious performance issues. I will also say that the last time the CEL came on, I went to get gas, and it shortly went off. I just assumed it was the gas cap. Now, it has come back on. Someone said it could be the cold temps we are having now down here in South GA but I wasn't sure what to think about that. Obviously, without the codes, I have no clue as to what has triggered the CEL to begin with. I'm paranoid because this car is my baby (and my daily driver) and I don't want to risk causing any long term damage to the engine. Any tips or insight would be appreciated. Thanks in advance.