From memory those values are used to determine the action upon getting a DTC. So certain bit patterns determine if MIL is illuminated, limp mode activated, code is active or hidden and a few other things. Some regions don't put as much weight on emissions related codes so they just have them logged as shadow codes.
Thanks, hmm so that is maybe an interesting point.
Maybe I am wrong, but I could understand that the catalyst routine never stops cause 29F4 & 29F5 are disabled ?
Let's say we find out the value to shadow (instead of disable) for 29F4 & 29F5, maybe it will stop to run the catalyst routine, while not popping a CEL ? (in my MOT they only check for CEL, they don't read coder from OBD)
EDIT: for example, i remember when flashing a US bin on my EU car, there was a problem (CEL) with 2A13 & 2A18 (DTML device that does not exists on EU car) :
- on my stock EU bin, by default it's not 56 since it is not supposed to exist, it's 01 (but why not 00, i don't know?)
- on US stock bins, it seems to be 56 by default and 00 to disable it
So i wonder what is the difference between 01 and 00 on mine, 00 is to disable the code, but maybe 01 is something more specific, and also disable some routines/functions related to DTML ?
According to that, maybe a different value than 00 or 56 could do something similar with 29F4 & 29F5 ?