I'm hooking up my rear O2 sensors after removing them 4 years ago. Now I can only find one of the square pin connectors on the main harness. Help me find where on the harness the two rear O2 pig tails are. I found one that comes off the harness near the rear of tranny sensors. Where is the other one?

 

M6?

 

Yes, M6. Do you know the stock location of the rear O2's and wiring? Thanks in advance. I'm installing them in my dual catted pacesetter longtube y pipe just for fun and doing a little research on the effect on A/F ratio and computer functions.

 

If your car is the same as mine. They should be up by the passenger side header.

I think the one you said you found is the furthest one back. So the other should be up by the header somewhere.

 

The after-cat sensor on the driver's side should have originally been on the Y-pipe, right below the cat, which was bolted to the stock manifold. The passenger side sensor would have to be further back, after the passenger side cat.

 

My bad. I was mixed up. That is where it should be. Up the header a little bit on the driver side.

 

Thanks guys I will look when I get back in town. I already looked in those locations so I'm worried that maybe in my haste I cut the pigtail off the harness.

The GM parts guys told me that both rear sensors are on the passenger side of the Y pipe. One pre cat and one post cat. I think they are wrong because if that were true then nothing would be monitoring the left bank cat.