pcr 2.1 need to be as you know unlocked before writing .
On this ecu pcr 2.1, ksuite (kess v2 or ktag) seem to be more stable than fgtech on pcr but work too sometimes: i get error with fgtech on one pcr2.1 but no problem with ksuite .
So if you have both tools , prefer ksuite seem to be more stable & flawlesslyand car run ok .
After you get you ecu unlocked in boot mode , with fgtech just remove boot and left pin connection , and read or write on bench .
On ksuite tools , you can’t read or write with ktag , only unlock . (alientech need to work on it…) with kess it’s ok , BUT , you can’t use the tricore module !
The problem is that the harness is plugged in the tricore module . so you have to build your own bench cable : just get a obd female plug on a scrapyard , and wire +12 gnd and can h/l (kline is not used but you can wire it it will make a universal bench cable) .
The trick to get communication error free on both fgtech and kess cable is to use a strong external psu .
when the tool id or read or write the ecu , the ecu will perform a kind of reset , and the big cap inside the ecu will go charging , causing a drop in voltage if your psu isn’t strong enough to handle it . THAT WILL CAUSE THE COMM ERROR . That’s the only thing you have to take care .
when i made test with many little psu (like one you get with your tools) i have seen 7 volts drop some time , so the ecu is shutting down and no comm .
you can use computer atx psu modded to work on bench (green wire plugged on ground to power on ) i think anything that can provide +12v 2A will be ok . i didn’t need more than 12v just a stable 12V . 14v unstable will not be ok
that’s why on the car you have no problem , car battery can handle the cap charging current .
There is no immo caused comm error on this ecu , psu is the problem !!
So in conclusion : good psu and obd home made bench cable , remove tricore module on kess = 100% tested bench flashing solution for pcr2.1 .