Good evening, I have spent a good amount of time researching this with no luck.
I have a newly acquired track only built 1991 Civic with a freshly rebuilt D16A6 engine in it, the car starts and idles fine enough but when looking through the S300 tuning logs I see the AFR is stuck at 10.0, throttle inputs do not change this value. So I do some digging in the engine bay and find the O2 sensor in the head is broken off with no signs of where it was plugged into or where it may be plugged into. This is where my issue is, I cannot find where to plug the O2 sensor into the wire harness to determine what O2 sensor I need to order. But have also read of some folks running with no O2 sensor inline. Any help in this direction would be greatly appreciated.

 

idk if you’ve figured this out already since you posted this in 2024 (if you have you should lmk how I’m having the same problem) but if you haven’t from what I’ve gathered the wiring harness connector should attach under the distributor in that bunch of wires where the temp sensor is. The problem I’ve run into with my car is that I can’t find a replacement connector for that wiring harness end. I have the o2 sensor and that half of the connector, that’s the easy part I was able to just order one from oreillys and it looks up to par but if you’ve been able to find a wiring harness connector in the year it’s been since you’ve posted this I would greatly appreciate hearing how you did it