'99 secondary O2 sensor wiring
 

I've had a full Stebro exhaust on my car with stock headers and no provision for O2 sensors for a while, just put on performance headers with primary and secondary bungs. I installed the primaries and found the harness coming around the rear of the heads, no problem. Fabricated my own spacers for the secondaries, but CANNOT find the harnesses. I am working with jack stands and floor jacks, not much room. Anyone have pictures/diagrams/input?

Not sure this helps you?

12 and 24 are oxygen sensors

That helps a little, shows where the harness heads to. I'm still having trouble finding the other end of the harness for the secondaries though...
where 12 connects to the car.