The ESP BAS light came on in my 2005 W163 ML 270CDI towards the end of a long journey.
From memory of similar threads I was fearful of it locking the gear selector and going into limp mode if I stopped or switched off.
The next day I re-read the threads and decided to change the Brake Light...
I cant believe it. i Have leak in windscree wiper system. Looked and common problem on headlight washer. Looked at mine on the front ad its just a hose. Filled up and water is just pouring out.
Someone has nicked both of the headlight washer things that come out of it.
I wonder what they are...