I have a BAMA tuner on mine, but put it back to stock before i had my emissions done and passed. I would start with removing that Diablo tuner then having it rechecked. I don't know what Diablos setup does, but i know any tuner can affect 02 readings and catalyst readings, however you did say you've never had a problem before. Have you recently had any check engine lights cleared or anything fixed for a CEL and had it reset? You should take it to a shop that has the capability of reading your 02 and catalyst monitors and see if they are reading, this is most likely your problem.
Last edited by XGC JACOBS; 05-24-2014 at 11:06 AM.