00 Maxima-CEL code 430 and 140

Hi everyone. I am new to nissan's and have a few questions regarding a 2000 maxima V-6 which I believe has the "federal" emmissions control system. After scanning the powertrain codes i came up with po 430 bank 2 cat below threshold, as well as po 140 o2 sensor no activity bank 1 sensor 2. My question is will replacement of the o2 sensor correct this condition or does it need the ecu flashed as other websites refer to regarding nissan's technical service bulletin. Also is bank 1 the firewall side or front of engine, and where is sensor 2? closest to cat I presume. The car is all stock with about 130K. Any info at all would be greatly appreciated as I have very little knowledge of anything but GM cars. Thank you in advance, Joe

... po 430 bank 2 cat below threshold, as well as po 140 o2 sensor ...

Try first resetting ECU: batt off 30min. If CEL light returns, replace the sensor(s), first one, then 2nd as/if necessary. Check connectors for the po 140.

Try finding info from a manual, 2002 most probably is ok; login http://www.phatg20.net/

Try first resetting ECU: batt off 30min. If CEL light returns, replace the sensor(s), first one, then 2nd as/if necessary. Check connectors for the po 140.

Try finding info from a manual, 2002 most probably is ok; login http://www.phatg20.net/

I have reset error codes with a scan tool, and they have returned. So i am assuming that is the same as interrupting the 12 volt supply to the PCM, but I will check the connector on the sensor and replace if necessary to try to correct. Thank you for your reply, Joe

These are 2 separate banks coming up, therefore I would believe the problems are un-related. I had the 420 come up on my 2001 SE and it was the pre-cat. About 1k if you have $tealership do it, I was lucky-mileage below 80k-under fed. emissions warranty. On my SE bank 1 is closest to firewall (odd cyl. bank), sensor 2 is one closest to muffler. These cars have 4 cats and 4 O2 sensors. Just more $hit to go wrong!!

... believe the problems are un-related. ...

Quite possibly. Still odd to have two different faults simultaneously. Maybe the ECU is throwing random numbers...

Stupid sesnor games: The big 'fun' is still to be experienced when microsoft viruses enter car software market, Fiat is testing...

True, one never knows w/ these rolling enigma's. When viruses come out I'll cut harnesses place an intake w/ carburator and hollow crappy cats out!!

True, one never knows w/ these rolling enigma's. When viruses come out I'll cut harnesses place an intake w/ carburator and hollow crappy cats out!!
Thanks for the info, every little bit helps, I am trying to do this for a relative not even knowing the location of the cats, sensors, etc. since I never saw the underbody of this particular car. It sounds like it won,t be such an easy fix as some other emission sensors I,ve done in the past..Joe