hi i had this problem the first time i installed my Injen CAI
. after a couple of weeks my cel came on also. i put the stock air box back on and it went away. a week later i reinstalled the CAI
and after a couple of weeks the cel came on again. this time i took my car to my mechanic and he ran a diagnostic check. the error was #420. he said that it means the catalyst system efficiency is below threshold. it sounds like we have the same problem. i did have to replace an o2 sensor a few months after i got my car but that was before i even got my CAI
. i just took my CAI
out for the winter time. do you notice any change in acceleration when the cel is on. my car seemed to have no pickup whenever the cel came on. take the CAI
out and take the car to the dealer. see if one of your sensors needs to be replaced. i've gone through 2 o2 sensors and my car isn't even a year old.