The warranty expired in October, but because I brought it in in September for this problem, it's covered.
I'm looking at the papers from the dealer that explain what was done - none of the codes are on them, so I'm not sure what the codes are.
There was an internal leak in the valve cover - they replaced that. They replaced the mass air flow sensor. They replaced the pre cat 02 sensor (apparently it had a malfunction). The first time, they just reset the light because apparently it was a gas cap code.
This time they called me and basically said they had some ideas, but were not sure because the light went off before I brought it into the dealer. It was on for a week. I brought the car in on Thursday afternoon, and as of now, it's still there.