I have a P0420 ODB code and from what I have seen on the postings that it is Catalyst Efficiency Low Fault Bank A. Cylinder #1 is located on Engine Bank A. My question is, which side is bank A, The front of the car or the firewall side? I love the car and want to try and fix this myself.
Thanks

 

Your catalytic converter is probably gonna need replacing. It's the one that comes off of the #1 cylinder bank. I've been there and done that. I also scoped my O2 sensors hoping that's what it was - but it was the cat.

 

http://forums.maxima.org/showthread.php?t=374481