I have this vehicle in today to check for a battery drain. Inital tests confirm a drain of 0.19 amps after half an hour. Next I carried out a full vehicle scan to check for any suspect modules etc, cleared out various spurious codes and rescanned with no codes returning.

Whilst checking for codes, I noticed that Tech 2 lists a function called battery quintessential drain optimization. I carried out this function which appeared to reprogram the under bonnect control module and hey presto, drain drops to 0.02 amps.

Does anyone know what this funtion does? I know the clue is in the description, but it would be lovely to know how it works. I always feel happier when I know what I've actually done!