The 99 I30 has been throwing the CEL code that indicates the rear (Bank 1 Sensor 2) O2 sensor needs to be replaced. I happened to have an extra NTK O2 Sensor (part # 24525) for the front (Sensor 1) just in case one of the fronts were to fail. Naturally the first one to fail is the rear (part # 24630) sensor. So I won't be able to use the spare that I keep in my workshop's stash of (most likely to be replaced) parts for the Nissans. Is this completely true?

My experience with NGK/NTK O2 sensors on the Q45 (left vs. right) is the different part numbers represent different cable lengths. While the part numbers and cable lengths differ, the sensor element part is the same.

For discussion purposes when you are in a pinch, is the O2 sensor (element) the same for the rear sensor (Sensor 2) as the front sensors for a Fed Spec model? If yes, the NTK part number is based on the cable length (and grommet) difference.

Also note Greg has posted some GREAT instructions about changing the rear O2 sensor at the following URL location.

http://www.nicoclub.com/archives/maxima ... ensor.html

As a side note, I was able to pick up a new NGK/NTK O2 sensor (part # 24630) for $53 and change (with free shipping) at Advance Auto Parts Online by using one of the discount codes from http://www.offers.com.

Now I know what I'll be doing next weekend.

That's a bargain for an NGK/NTK sensor. I usually get mine from Sparkplugs.com or Amazon.com, whichever has the lower price.

I believe the internal components of the O2 sensors are the same though some have heating element.