Its one of the rear O2 sensors, it does not effect the performance of the car at all. Its there to check cat efficiency for the OBD2 govt requirements. If you don't want to spend any $$ then I would just leave it alone. If you ever get an SCT chip the rear O2 sensors can be turned off.
Well, it was pretty cold this morning. Like 20* I think. It had only been running like 10 minutes before I left, and the engine wasn't warmed up yet. So I'm thinking it might have been the cold weather.
I went outside and deleted the code. If it sets again when I leave in another hour and a half I'll look more into it.
Your sensor is electrically heated, which basically means it does not need heat from the engine to start working. Older O2 sensor designs did. 10 minutes should have been more than enough time for the O2 sensor to heat up so I doubt the lack of running time has anything to do with the code.
actually it could be that your sensor was clogged with something like part of your cats and the exhaust blowing by it could have blown it away. Or it could just be that your computer hasn't thrown the code again yet. I personally would just replace it because I had the CEL light. it bothers me. I highly doubt the wiring is bad because it's wrapped pretty good down there. i would later do what justin says and turn them off, I did that to mine and now I have 2 spare o2 sensors.
see, just replace it, it might cost ya somewhere from 40-60 bucks for a new one, hopefully you can get it cheaper. Try ebay or terry at mdwest mustang. i got two from him for 35 bucks if I remember correctly.