Here's a quick preface to my problem. I had a rattle under the car when I bought it so I ended up ordering a new down pipe with catalytic converter. I took the old pipe/cat off only to find there was a broken weld and the heat shield was crap. I had it re-welded and scrapped the heat shield and put the old down pipe/cat back on, installed the 4 O2 sensors and ever since I've had a p0138, p0420 and p0430 code. Any suggestions? Can someone explain which bank is which (where the pre-cat O2 sensors plug in on the drivers side of the engine vs. post cat O2 sensors which plug in the passenger front corner) and which sensor is 1 vs. 2? I bought two new walker O2 sensors which I understood when I ordered them that they could be used either before or after the catalytic converter but just don't know which old sensors to swap out.

Tyler

 

let me just say that i find it histerical that the XJS uses post cat o2 sensors to adjust AFR.

 

The front 3 cylinders are A-Bank. Pre-cat sensors are "1".

Can't help with which connectors are which, sorry. If you get them wrong you'll have to find someone to re-orient them properly

P0420/430 are often caused by air leaks as well

Cheers
DD

 

Which ones?

My '88 XJS had pre-cat Oxy sensors

Cheers
DD