Will do. Hopefully I can do the ridiculous Drive cycle correctly that Mitsubishi requires to clear the I/M Readiness monitors and the p0421 code in the PCM so I can get this thing smogged! Not sure if you have the tech bulletin that describes the chicken dance you need to do to reset these. If not, let me know I have a copy-

 

I do not have the tech bulletin. If you can sent it to me that would be great. Thx

 

here is the bulletin that pertains to your Year/model for thje correct drive cycles to clear I/M monitors

 

You found it Good luck to both of you. That sensor can be a pain to get out. It's pretty tight in there, but not as bad as Bank 2 Sensor 1. That one is absolute pain.

 

Yup, Bank 2 sensor 1 requires you to remove the driver's side wheel and access it through the fender well. That's the ONLY way I have found

 

I've managed to do it laying under the truck. Not an easy way, but I was lucky because mine is raised. If you have to install non-foulers on one bank, I'd play safe and install them on the second bank as well.
BTW, the sensor and non-fouler do fit on the Bank 2. It is tight and you have to use an open end wrench to install it (not enough space for a ratchet).

 

Hmmm.... good advice on installing on the other bank and what to use tool wise. I think I will do live data on the scanner and monitor 1 vs 2. I am guessing they both should be close in readings and not fluctuate too much, correct?

 

Yes. They both behave very similarly. If not - one of them is not working right. In fact I believe on the later production models, Montero only has one post cat sensor.

 

Thanks HunterD. Ok, theoretically if the cat is bad, then it will read correctly and fluctuate between .01 and .07 v if i'm not mistaken. if the cat is good, then fluctuation should only be in the .01-.02 v range. Would it be possible to wire the output of the correctly reading O2 sensor to the side that is not by using the signal side wires or is the computer smarter than that?? My understanding is that it is looking for specific parameters (voltage) behavior on each of the four monitors (O2 sensors)?

 

Musicmanjer, that is 100% correct. A properly working cat will "lean out" the gasses coming through it during the catalytic reaction. So the reading on the post-cat sensor will be lean (low voltage ~0.2v). If the catalytic converter does not work, the post cat sensor will read full on fluctuation from 0.2v to 1v and it will look just like the pre-cat sensor readings. When PCM "sees" these fluctuating readings on the rear sensor, it will set the P0421 code. I do not know if wiring PCM sensor inputs from one sensor will work or not. PCM might "catch" the fact that the wave forms are identical, when they should be off by few milliseconds.

BTW, as I was thinking back about installing the non-foulers, I remembered that on the driver side it is easier to assemble the O2 sensor and the non-fouler, and only then screw them both into exhaust port. Otherwise you will not have enough clearance between the transmission/engine and the exhaust.