Am also searching through the workshop manual for the gearbox heat exchanger cooling side , just trying to cover all bases so to speak

As there’s the flat plate gearbox cooler with the 2 x pipes for the atf oil side and other 2 x pipes from the engines water cooling side

Will come back to u if I find out any further details for u mate , ie, if the overheat temps are in the workshop manual etc so then at least we will know what the trigger points are so then could look via the live data on the scanner

Blimey these workshop manuals have a lot of pages , finally managed to find was I was looking for regarding ATF cooling side

Wished to see what the temperatures were so then had the data as a comparison if u wished to check what they were via live data on ur topdon

Just had it in the back of my mind if there was anything that could also cause issues , ie, if there was a thermostat that say was letting by causing higher temperatures to reach the atf cooler leading to an extra higher reading than normal

Hope it’s useful mate and expect I’m totally off the mark but wished to try and cover all the possible scenarios so that the error could be resolved once and for all with the least amount of agro