Auxiliary battery malfunction

[Bazrides]

Hi all
I have a Mercedes ml250 , ive recently replaced the auxiliary battery as I was getting a warning “ auxiliary battery malfunction “ after replacing I am still getting the same warning light , any help would be appreciated please . TIA

 

[gr1nch]

I've not got the answer yet, but I'm actively testing and reducing to find one!

Am in a similar situation with my 2017 W222 - the "Auxiliary Battery Malfunction" message and Distronic non-operational - and I tested today that battery (its a pain to get to) and it is at 100% charge but still the error occurs. I think the possibilities are issues with:
- the main battery
- wiring
- a "stuck" flag in software which thinks there is an error with the aux battery, so disables functionality that rely on it and reports the calculated cause erroneously.