All 4 new O2 sensor replacements on a Jeep Wrangler TJ 2001 4.0l i6. by Ken Killeen

So, despite weeks of research and part hunting, I finally found all 4 new oxygen sensors for my jeep. It has been advised that many after market sensors provide poor readings or longevity with Wranglers, having different start up times etc. NPK parts ate recommended,  and due to the numerous models and variants of wranglers and even there sensors, I was satisfied to find them. Sadly, as Jeeps are, unexpected issues arose during install. despite the correct parts, my plugs seemed older, from pre 2000 models. this is a problem I've found often in my 2001. it appears to be a mix or hybrid of older and newer parts, and make more complicated that this was a Mexican produced variant and now an Australian import right hand drive! needless to say, many of the plugs were offset enough to warrant modification or rewire. But all were successfully installed in the end.
I recommend a cold engine despite all the advice on heating (heat causes expansion of metals and I need not explain that further,  lol).  heat impeded removal for me at least. I recommend an appropriate o2 sensor tool as it makes life that much easy given this task.  WD40 was used to help loosed one sensor that had rust fused. all others were quite easy to remove.  This video documents the 20 or so minutes of work it should take providing you don't encounter severely siezed bolts or have to rewire everything like I did.
hope this vid helps anyone who encounters similar issues.  

happy cruising  ;)
Kenny