Today I found the O2 sensor under the pass seat was not connected, so I did that. Reading unchanged & fixed. What to do? I started examining the part on the driver's fender into which the probes get inserted. Looking carefully, I only saw a metal connector in hole #1. There was no metal receptor in the other holes; & when I examined the black feeder, with the four wires inside, I found the wires were completely unattached-their ends had been cut off & when I popped the top plug there was only the connector for #1 - everything else was empty of connectors & wires. (The connectors & plug for the three holes in the semicircle was OK). That explains why I had no readings. This now seems to be way beyond me, but I could be wrong. Can this be fixed/rewired & connected, do I go to a good indie or dealer, or should I let it go? How can mixture be set now?