Hey again all. Well, I ended up keeping the car, only to have it catch fire a few weeks ago. I pulled into the driveway, and the back of the engine was burning. It wasn't a big fire at all, so I ended up putting it out with a pressure washer (I know, not a good idea, but it was burning Lol), blowing off all the vacuum lines, and a couple of wires (O2 and MAP) in the process. It was towed to a shop where they determined one of the rear spark plug wires had caught fire. They replaced that wire, the vacuum lines, Oxygen sensor, re-attached the broken wires, and sent me on my way. By time I got the car home (around 30 minutes), the Check Engine light was on. I did a code reading, and it came back as P0131 (HO2S Circuit Low Voltage Sensor 1). I brought the car back to the shop, where they had it for almost another week. They finally looked at it, and told me the reason the check engine light was on, was the 'intake manifold gasket' was leaking. They said this would trigger the P0131 code. They cleared the code, but it was back by time I got home again (around 30 minutes). From what I can figure, this isn't true at all, but I wanted to see what you pro'* thought.

For the record, prior to the fire, the Check Engine light was not on, and never was. I actually had it looked at quickly in my driveway, and we fired it up. It didn't run all that good (which is to be expected when most vacuum lines are broken, the MAP and O2 sensors disconnected, and a plug wire destroyed), but there was no check engine light...Not that I took it for a drive cycle, mind you.

Thanks all, and any help is greatly appreciated.

My first thought is that the insulation (or the wiring) in the O2 sensor harness has burned or melted away, making a short circuit (or open circuit).

Inspect that wiring very carefully; maybe post us some pics.

Thanks for the info Argazela. I had the wiring checked, and all seems well. Nothing is melted, burned, or unattached.
Any other thoughts?

what is the code for o2 sensor?