Marco Stanco

Hi all i just installed an after market carplay retrofit on my 2016 c300, and after doing so i started my car and got a “auxiliary battery malfunction” in red writing on my dashboard. This immediately sent me into a panic thinking I broke something, turned the car on and off a few times it didn’t go away until i stepped away from the car for 10 minutes and came back now the message was gone.

Came back today while I was driving, red message and it would beep, disappear for a second and come back and beep again--- then the letters turned to white instead of red and it stopped beeping but still flashing on/off.

My engine start/stop function is still working and everything so, whats really the problem? Should I just take this stupid carplay thing out? Do you think I broke something? This is my second time doing a carplay (the one i had before was older and i wanted the newer model) so I knew what I was doing… I don’t know just a little worried lmk!

chassis

Time to replace the aux and main batteries. All late model German cars are sensitive to less than 100% battery(ies) condition.

Marco Stanco

Yes I know that, but you don’t think it’s strange this message popped up just after installing the carplay module?

Also, i just purchased this car from mercedes 2 months ago and they put a new battery in for me, so wouldn’t be the main battery.

chassis

No I don't think it's strange. You invaded the electrical system on a vehicle with possibly borderline main and aux batteries. Time to replace both of them.