Ok, here is a quick question... a few days ago my SES light came back on... it was the code again for the rear o2 sensor. Before I decide to spend more money for a new 3 wire sensor I was woundering if someone has used a 4 wire sensor for the post cat. Pretty much the difference between the two is extra ground wire... theoretically it should work. The only reason why I am asking is b/c i have a brand new o2 sensor which is a 4 wire unit that I would like to use instead if spending money on another unit. Anyone done this before?
Thanks!

 

OK I am confused as hell now.... I finally got some time to change my post-cat o2 sensor. I got one online, brand new, plug-n-play not the universal type. It is a 3 wire unit with the wide plug. When I got under the car I noticed the the one bolted on was a 4 wire sensor? I know that the previous owner replaced it about 2 years ago.
Did I get the wrong unit?
The car is 2000 Maxima SE Fed edition (only 3 sensors) I am replacing the one between the cat and the resonator.
Is it a 3 wire or a 4 wire o2 sensor?