Did you look in the spare wheel well area of the trunk?

 

Not there.

 

ECO start/stop battery, as mentioned should be in tire well.

 

TCKT B8,

I have the same issue, 2011 E 350, error message on dash, however, battery location is a mystery.

Did you find your aux battery?

 

2011 E350 Auxiliary Battery Location



The picture below show the 2011 E350 Aux Battery location which is basically behind the driver's dashboard to the left.

 

I found another aux battery location PDF for a 2010 W212 at this site: 2010 E350 (W212) Aux Battery Replacement - MBWorld.org Forums

 

Boat,

Thank you!

You rock!

 

I just changed the aux battery in my 2012 E350 today and it's there in the location shown in the post above. Here is a picture of the back side of the cover showing the anchor points along with a picture of the aux battery.

 

Thanks, JMillerman, and 6 speed. Very helpful photos.

 

E350:
- Not ECO (B03) aux battery (transmission selector 1.2AH) located in dash
- ECO aux battery (starter 12V/12AH) located in trunk

 

I've got a 2015 E250. That 1.2Ah battery is NOT in the dash compartment.... Can it be elsewhere or is it missing??

 

Should have starter battery in engine compartment & auxiliary battery in trunk (B03 start/stop). Post or PM VIN to confirm.

 

Hey the VIN is WDD2120362A922465

Plz help!!! I'm lost here...lol

 

Vehicle does not have dash battery.

 

Well shit.... thanks a lot man!