Just out of curiousity, is anyone out there driving their 4th Maxima without the rear o2 sensor (the one post-catalytic)? If so, any difference?

 

If I remember right, all the rear O2 sensor does is measure the output of the cat. It does not affect anything drivability related, it just monitors the efficiency of the catalytic. Removing it will cause a CEL to iilluminate however, and if you have emissions you will likely fail (in my area you would fail with it every time)

 

I drove around with it completely out of the cat for a while since my friend ruined the threads while removing it. I felt no difference in performance and saw no loss in MPG.

My CEL only came on every once in a while. I would reset it and it would go away for some time. I've replaced it with a direct fit Denso.

 

went with Denso as well. got my two front banks in today, this weekend they will go in. Hopefully they are not rusted into the sockets

 

With the age of these cars, they probably are but they shouldn't be too hard to get out. Be sure to put some anti seize on the threads of the new O2's.

 

Heat on the O2 socket works great; needed my propane torch to get at least one of mine out.

 

When I replaced everything but the headers I ran without the downstream O2 sensor and it had no effect on the performance. It just gave the P0420 cel code. I finally grinded it out of that intermediate pipe and installed it 3 months later.