Thank you HunterD. So, then I will install the O2 sensor and non-foulers as a unit. I was thinking though, if I want the sensor on the bad Cat to act similar to the one on the good cat, would it make sense to just install them on the one?
The pre-cats are virtually unavailable, and since were here in Ca., if I did find one, it would probably be very cost prohibitive. I am crossing my fingers on this mod. I will use my live data on the scanner to monitor the difference (voltage) after the non foulers are installed to see if there was even a difference. All I have to do is to get the catalyst monitor to go to ready. The O2 and O2 heater monitors have gone to ready once, but with the IM P0420 coming on, it reset them, thus having to begin the monitoring cycle over again.

 

It makes no difference if you have a non-fouler only on one sensor vs on both, unless the second bank converter is also on the verge of giving up. What non-fouler does - it makes the sensor reading look lean by restricting how much fresh exhaust surrounds the sensor. On the monitor it looks just like a working cat.

 

Allright, so now that I understand the process, "fooling" the O2 sensor by restricting the amount of exhaust gases passing by the sensor is essentially what is happening, thus, in theory the O2 sensor will send a "modified" reading to the PCM simulating a good cat? I will owe you dinner if this works. If you're near Sammamish, I know a great steakhouse!

 

I might take you up on that offer

 

I have finial install the non-foulers yesterday. Musicmanjer, thanks for the driving tip. After I installed them, I disconnected the battery negative to clear the code because I do not have a OBD2. I then followed the driving pattern and drove about 35 miles and ended at the inspection shop. I passed with flying colors.
I was able to unscrew the O2 sensor but I was not able to unplug it. I was not sure so I did not force it. The wires is just a little twisted. Do any of you know how it is on plugged?

 

Glad it worked for you
The plastic plug has a spring tab that holds it securely. The tab on these plugs is very tight and it is comfortable to unlock it if you can get your hand completely around with the thumb pressing on the tab. Unfortunately, due the location for these connectors does not permit such ease of operation. Sometimes it helps to push the connector IN as you are depressing the tab, then it unlatches.

 

I am looking for O2 sensor one1 off of bank two2, I want the sensor circled in red so I can see it specifically and perfectly and know exactly which one to replace, off of a Montero sport XLS, I would like these pictures immediately or as soon as possible

 

Not sure if this will help. It's a different vehicle (full size Montero), but B2S1 will be in roughly the same place. Look for it right after the exhaust manifold on the driver side BEFORE the small pre-cat.

 

I just searched thru my 2002 Montero Sport 3.5L engine rebuild thread and folder on my computer. That thread is here. Post 119 has some info on the oxygen sensors https://mitsubishiforum.com/forum/mi...tero-sport-14/

Regarding "sensor circled in red" all I can figure is you were looking at my marked up drawing of the exhaust system from this thread Post 6 https://mitsubishiforum.com/forum/mi...removal-47301/

Best I can find for you is attached here. The last picture shows 3 of the 4 O2 sensors installed. Hope this helps you.

 

Now everyone can use this thread as a reference. Thank you kind sir.