I have a E350 2014, received the signal Auciliary Battery Malfunction. What is it? is it serious, should I take it to the Dealer under warranty?

This may help, Copy and paste....http://www.benzworld.org/forums/w212-e-class/1572334-auxillary-battery.html

If it is under warranty - take it to the dealer for inspection. IF it is a battery and if it is not under warranty - just tell the dealer "thank you" and go buy it elsewhere for a lot less money.

Small aux. Battery located under dash on drivers side, enables trans. To be shifted out of park if main power is lost.

The auxiliary battery also is used in the ECO functions to restart the car when it 'shuts off' while stopped and operates the HOLD function (keeping the car from moving) while stopped for a traffic light.

Also, the aux battery in my 2014 E350 is in the trunk under the spare tire.

Yes it is in the trunk, not in the dash. About $145 at the dealer.

Where is the aux battery located in the e350 wagon?