Hey all I have an 2002 Montero Sport. I am working on resolving code P0154. I replaced the Bank 2 Sensor 1 oxygen sensor and the check engine light will not clear. Upon further investigation I read that there was a PCM update regarding this issue. TSB−04−13−002REV found on page 22 of this bulletin:

https://www.mitsubi****echinfo.com/e...atachart-2.pdf

How would I go about updating the PCM to clear this issue? Are there any alternate fixes I could try.

Any help appreciated, thanks in advance!

 

First, I was not able to open the link you provided.
Second, From what I remember, the PCM update was to re-map how PCM interprets the signals from O2 sensors, and therefor when O2 related codes get triggered. The original programing was too sensitive and would trigger Check Engine Light even when there was no "true" malfunction. In your case, the P154 indicates that there is no activity on the sensor. I'd start by checking wiring to the B2S1. That sensor located in a hot zone and wire harness may have gotten damaged by exhaust or some other thing. The damage may be the reason of no activity.
If you do want to get PCM re-flashed, the only way I know to do it is to go to the dealer. In my case it was free, but was years ago when vehicle was still under warranty. I doubt the 2002 model did not yet get the re-flash in all these years.