to answer your question, my understanding is that if the enduro plug is not fitted, and you have ESA, when you set it say in "DYNA but with ESA on soft" then when you switch off the system resets to the default "DYNA - Hard, ROAD - Normal and RAIN - soft"
With the plug in it will keep your individual ESA setting for the mode you were last in.
It plugs into a socket hanging around under the seat. Mine had to be coded to the bike by the dealer.
