I had a 224 cam with duals (no cats) and long tubes. I had 50,000 miles on the o2 sensors on the car with no problem. I put back on the y-pipe with cats, and the cat back to get my inspection sticker, and the SES light came on. It was originally reading bank 2 sensor slow response, and a maf code. Then, I had my x4 cam installed, went back to the duals for the tune. After the x4, my codes were cleared, and the SES light reappeared, to read bank 1 & 2 along with the maf code. I have since reinstalled the catted y, and replaced to o2 sensors from a friend's car that I know worked, and my SES light is still on. Any suggestions on what else could be wrong?