Just started today... taking in next week for A1 service anyways ...

do they replace it if it's bad? Is this the trunk one?

Pretty sure it's the one in the trunk. Has the car been sitting for a while?

Yep, sat for a week, but drove it a couple days and no problems then today with the message? 2014 with 17k miles ....

edit: tonight no message warning ... weird

What is your in-service date? Batteries usually last me 3-4 years depending on how often the car is driven.

Peter-Had that malfunction as well-Dealer told me aux battery was primarily for the start/stop function (Same as your dealer). Incidentally, Im due for A1 service as well. Was quoted $700. Is this possible?

I have heard there is another battery below the steering wheel location. If it's the battery in the truck, it should be an easy diy because it's easily accessible.

Mine was covered under warranty when it went bad shortly after taking delivery of my 2014 CPO.

My 2010 has it mounted up above the driver footwell. Kind of a pain in the *** to get it out but was straight forward. Not sure if the facelift W212 is different...

My in service date dec 2013; I can't imagine paying $700 for that!!! Will definitely try to get them to cover this under warranty

thanks for all the info

Is $700 for the battery and A1 service or just the A1 service? That seems really high.

I just had my 20,000 mile service done, and it was $339 + tax. I paid extra for cabin filter and diff fluid change.

They also fixed the front grille whistle under warranty.

Just realized ... no aux battery no brake hold??

Yes to both.

Correct.

As mentioned above my aux battery is behind the cover on the driver side of the dash that is normally covered with the door closed. But i have a 2010. So not sure if it has changed locations. Very easy to swap. Battery is like $50-75 i think. Don't remember

thanks guys

Aux battery was replaced under warranty, $197 to check/test and then replace, I paid nothing. A1 covered under my service plan. Didn't have them do the adaption because quite honestly my car is running smooth and I didn't want to mess with a good thing, I've made that mistake before

I just received this aux battery malfunction this morning. 14 E63 wagon with only 14k miles and I hope the CPO warranty will cover this.

It should be.

Also '14 Wagon, mine failed the day after I took delivery of it. It was replaced under warranty.

-chris

Just had my AUX battery replaced @ 44k miles on my 2014 cpo / extended

100% warranty

Kinda lame that parktronic and presafe stuff stops working when that battery does?

On my way to the dealer and the warning went away. I believe all dealerships have some sort of symptom canceling force field to temporary disable any issues you have with the car when entering the service center lol.

There will be stored faults. They shouldn't give you a hard time about it, the batteries are relatively cheap and they fail very often.

Had mine replaced under warranty as well, no questions asked.

yup... all rattles and creaks get cancelled too... and any vibrations

Booooommmm......I read the post and get the error message.....90 mins later problem is solved by the dealer at no cost under warranty. Now only if we could turn ECO off by default, I think this would be less of an issue!!!