Buddy of mine has a '99 F150 4x4 with the 5.4 V8. He was off roading it a while back and said the check engine light came on and has stayed on since. He went to have the yearly emissions test done Tuesday and it failed, said there was a problem with the O2 sensor circuit on bank 2. I crawled up under the truck, and sure enough found the wire just dangling there off the O2 sensor. The male plug on the harness that comes out of the truck is ripped of, just the wires dangling there. The O2 sensor itself and the plug on it is fine. So I guess when he was off roading, some weeds or something must have got caught on the O2 sensor wiring. Anyway, I snagged another plug while I was at the junkyard the other day. Went to splice it back into his truck, and noticed there are two black wires and two white wires. The wires don't have any hash marks or anything on them to distinguish them apart, just two black and two white. So I have a 50/50 shot of hooking the wires back up how they came loose. As long as the white wires are matched up and the black wires are matched up, does it matter if one or the other is reversed? Below are a couple pics of the female plug coming off the O2 sensor itself. The male plug from the truck that plugs into this is gone, just the frayed wires hanging there.
Fixed that this morning. Check engine light went off for about 15 minutes, then came back on. I don't remember exactly what the codes were, but looked them up, one was insufficent EGR valve air flow, and the other was excessive EGR valve air flow! At the same time.. The truck doesn't idle steady either, it idles at about 1,000 RPM (too high to begin with) and the idle surges to about 1,800 over and over like you hear old lawn mowers do some times. No driveability problems though.
