Is the catalytic converter located on the firewall side or the radiator side of a 2002 Nissan maxima? also is the firewall side the right or left side?

 

There are two pre-catalytic converters off the manifolds (one on radiator side and other on firewall side) then there is the main catalytic converter further down towards the center of the car.

 

how can I find out which catalytic converter is going bad? I was just told that it needed to be replaced but I was never told which one

 

If a cylinder in the front is burning oil, more than likely the front precat. If it's burning in the rear, probably the rear precat. Usually the front one goes first as it's a weaker honeycomb.

 

What code are you getting to know that a cat is bad? The code will tell you which one.

The bank 1 side is the firewall side, also referred to as the right side.
Bank 2 is the radiator side, AKA the left side.

Reading through cat info here and around the web, I've noticed that some people confuse the terms upstream and downstream; so watch out for that when looking for info.

 

The codes don't mean jack. My 1st 3.5 grenaded from the cats without a cel.