I spoke to a dealer today and the Rear Heated O2 sensor was indeed recalled.Mine was already replaced in 98 by the previous owner.Pls talk to your dealer and if you're lucky (i.e if your previous owner has not got it replaced)you might get a new sensor.

good luck,
Jay

 

I had one replaced and got reimbursed by nissan at 48k. However last week, I had to shell the money out since it had 68k. Nissan extended it to 60k.