My 2003 E320 had a battery malfunction warning come on red on the dash. I called the dealer and they stated that seeing the malfunction light was red and not yellow that one of the two batteries was bad. Mercedes Raodside came out and checked the batteries and said they had correct voltage on them. Seeing the car starts, the tech said he wasn't replacing the batteries cause thay showed good. He stated I need to take it to the shop so they can test it further. I will be taking it soon, but does that warning light also mean it could be the altenator? Sometimes the warning is not showing the malfunction, then I restart the car and it's on again. Could it be just a sensor sticking? Has anybody else had this problem?
Thanks!

 

Your car does have issues with that. But my buddy has an 03 and his light comes on and off at times and ive told him to let it go and not worry about it cause all checks good. Hes been driving that way for a year now. Could be that one of your batteries might be getting weak or your bcm..battery control module could need a software flash or just a new one. There is also a auxillary battery relay that joins the 2 batteries when needed and maybe thats going bad too. I guess it could be your alternator but its hard to say.

 

The aux battery did just have 10.29 volts on it when measured. I hope it's just that. I've read people opening up the battery and adding water and all is fine. It is a sealed battery and you've got to pry the top off. Think I'll just replace. Thanks for your help!