2016 Mercedes E250 (Bluetec diesel) with run-flat tire shows "Auxiliary Battery Malfunction" after tire change


We recently got a flat tire on our diesel Mercedes E250 (Bluetec) so we took it to a local shop (with high ratings, but ratings can be for different reasons) and were told that there was a nail in the sidewall of the passenger side rear tire so that had to be replaced. We have run-flat tires (which the tire shop did not seem to notice, which caused us some concern about their competience, but we were already in the shop and had to find a solution, this being the middle of the country) but were successful in mentioning that to them and they replaced the tire with the Bridgestone DriveGuard which is a runflat tire. Anyway, immediately, we have had this “Auxililary Battery Malfunction” message go off. The car engine stops and starts when idling just fine, and so I was wondering if this can be related to some setting not being switched on/connected when the tire was being replaced. Is it simply possible that this was a coincidence that the Auxiliary Battery got busted at the same time as the tire was replaced? Thank you in advance for your thoughts.



I dont think it has anything to do with the tire.
Mercedes-Benz Auxiliary Battery Malfunction (youcanic.com)

Did a quick search. Doesn’t appear to be linked with tire change. https://thebatteryshop.com.sg/auxiliary-battery-malfunction-mercedes-benz/

Thanks, so when the tire is changed, isn’t there something that goes back to the display to inform the driver of the tire pressure? That is why (along with the fact that they did not originally spot the run-flat tire) I thought that there was a possibility that this had not been hooked up properly.

Also, is it possible that the auxiliary battery is low on charge? In which case, is it possible to charge it? I do have a trickle charger. The car had to be jump-started and so we drove around for 20 minutes before we went to the tire shop. However, at this time (before going to the shop), there was no “Auxiliary Battery Malfunction” warning.

Seem clear that the battery was failing before the tire was replaced, I don’t see how you can blame the tire mechanic.

the tire pressure sensors have their own lithium ion batteries inside the TPMS sensors. they usually last 5-10 years

OK, good to know. Was concerned about his attention to detail since he did not notice that the tire was runflat when ordering a new tire (the order had to be changed), that is all.

OK, thanks, so no connection with the display.

if the battery dies in the tire pressure sensor it would probably not show any tire pressure for that tire.

Thank you. Is it possible that the auxiliary battery is just down? The car was not driven for around 3 months because we waited for our shots to become useful before going to the tire shop.

After 3 months of storage the battery will need to be recharged.

Thanks, it is strange that the warning did not show up when the car started after 3 months (though the main battery had to be jump-started). Is the auxiliary battery charged in the same way as the main battery (which seems to be fine and fully charged now)? Of course, I have to locate it. Thanks again!

I suspect the algorithm to monitor battery performance requires several drive cycles. Most cars do not provide this warning system.

I see, can the auxiliary battery be charged via a trickle charger? I have a trickle charger which I have used to charge/maintain my main batteries (of my 1997 Volvo 850) or is some other charger needed. Thanks a bundle!

It appears that the auxiliary battery is a small AGM battery, don’t try to recharge this with a common battery charger, it can be damaged.

Use the vehicle for a week and see if the battery regains a charge.

See the weekend-warrior video link.

Thank you to everybody. I will run it for a week and see and then report back on what happens.

This indicates a tire replacement is required, regardless if run flat. Really two tires should have been replaced with new tires going on the rear. If your vehicle is AWD, consider replacing all the tires.

The battery situation preceded the tire replacement.