My apologies first off. I'm sure this is a topic covered before.<p>I bought a used 2005 S40 T5 a little over a month ago with about 52,000 miles on it. After about a week and a half, the check engine light came on. I read a few forums and threads and they mentioned it might be that the gas gap wasn't on tight enough which, sure enough, it wasn't. I tightened it, the light went off. About a week later, the light came on again, only this time it wasn't the gas cap. I took it in to get looked at, they told me it was the catalytic converter and they were going to do some work to fix it. From what I gather, the light didn't go off, so they told me they would replace the O2 sensors. They had the car for a week and a half, I picked it up last night, and on my way home from work today, the light came on again. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0"><p>Does anyone have any suggestions as to what it might be? I would greatly appreciate any advice whatsoever. Thanks in advance for any help!