Hello Everyone....ur probably not going to be happy with this....but the problem is MORE then likely the catalytic converter...which can be pricey....my Check Engine Light was on for a veryyyyyy long time....Im guessing almost a year...car ran fine...I had my scheduled maintenance...oil change, tune up that sort of thing...but I had to go and get my emmissions done...and my light was still on, so of course they dont pass it...I had to go and get it checked and it turned out to be the catalytic converter!...Hope this helps!!