well i am hoping its just the battery,on the lead up to christmas it was taking longer for the eco to turn green then it didnt come on at all one day then it was failing to come on everyday but only after the first start of the day and it was slow to turn over yesterday morning but this morning it was back to normal starting and the eco light was yellow but after about 2 mins it had gone green. but i will keep you posted about how its performing.When you figure out the problem, let us know.
Mine has never worked since 2015 when I purchased it - C204 350.
Same issue, the eco turns off completely.
Mercedes couldn't fix it, indy couldn't fix it, new aux made no difference, new main battery didn't help either although it seemed to happen more often before...
Maybe 80% before and now 50%
I even bought an iCarsoft but ther are no menus or data on the eco system.
Straight after the main has been charged either by driving the car then switching on/off or straight of a charger it will normally work ok for a few miles but soon reverts to switching off completely...