I have been getting O2 Bank 1 & 2 Sensor 1 alarms frequently, so figured it was wiring issues coming back to haunt me. So instead of stripping wiring harness apart I ran new wires all the way to all four sensors (no common wires now), so the issue will be easier to identify. Seemed to work for about a week, then alarms started again, so back to the O2 relay, and found the power input to relay coil was broke down to last few strands. This was also main power to ignition, so clean it up and solder back in place on fuse block. Runs much better now, but intermittent O2 alarms are still active, so grabbed another O2 sensor off the bench that used the same wiring plug as my pre cat sensors. Even an ignorant mechanic can find something once in a while. That O2 sensor gave O2 readings on startup, where "old" sensors started giving signals around two miles out. As both O2 sensors were doing same thing, and were not always alarming at same time, and were both only around two years old, I had been thinking it had to be wiring; WRONG.
Good news Amazon has upstream Sensors for $25 that fit, not universal. Ordered two.
