auxiliary battery malfunction

[Drey27]

Hi All,

My car sat with the dealership for 2 months and after received the car back I got a "auxiliary battery malfunction mercedes" on the dash and so I thought maybe it needed charging or replacing. I did some check to see the condition of the battery and the volt meter is showing a good state of charge of 12.6V and I also hooked it up on the charger which then gave a Full Charge reading. I plug the car onto a rearder and it has given

C073300, "Read fault memory of control module. "N10 ( SAM Control Module)"
B1E211B, "The buffer battery has a malfunction. The limit value for resistance has been exceeeded."

I've wire brushed the contacts but the same error keeps coming back.

My question is, is the voltage reading not a good indicator to wether the battery is still in a good state of health, or should I be check something else within the car?

Many thanks.

 

[Diesel Benz]

Which car is it? Cannot be the 2008 CLC?

I replaced the (12 Ah) AUX battery from my W222 twice for the same fault code. The old battery had perfect voltage when not loaded, connecting a 21 W bulb and the voltage dropped several volts (cannot remember exact figures).

 

[Drey27]

Apologies, I need to update my profile, its on an E class coupe 2015.

I guess I would just be replacing it and see how that goes. Thank you.

 

[Ted]

Open circuit voltage is not necessarily an indication of a good battery. You would need to have it load tested.

 

[Drey27]

Open circuit voltage is not necessarily an indication of a good battery. You would need to have it load tested.

will do that! Many thanks