Auxiliary Battery Malfunction
Senior Member
Joined: Jan 2013
Posts: 304
Likes: 75
2022 AMG GT 53, 2020 Sl450. Did drive 2018 S450
Replaced it. Easy to do. Cost $150 for part from MB. Takes about 30 mins to do. After you remove the three screws holding the fuse box in place don’t be afraid to yank on it so it brings the battery out so you have space to remove and replace. Thx all for comments.
Senior Member
Joined: Jan 2019
Posts: 497
Likes: 196
From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
That is my exact same story. Didnt use the car for about 2 months. Planned a roadtrip and that morning aux battery message came up. Figured it would charge up going down the road. Well of course 25 miles down the road the distronic and cruise would not work. 300 miles later it did. Then it didnt. It worked intermittently till we got home, 900 miles. Changed out the aux battery, no issues. So there is something in that circuit that effects it. Good luck
Junior Member
Joined: Oct 2007
Posts: 74
Likes: 16
From: Chicago
2014 S550, 2013 GL450
I just had mine replaced on my 2014 with 112K miles. I was told the only thing the Aux battery powers is the eco start/stop and it is a backup to release the parking brake if the main battery dies.
Senior Member
Joined: Jan 2019
Posts: 497
Likes: 196
From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
I was told the same thing. But was the first time the aux battery went bad on this car and I immediatly has cruise control issues and distronic issues. Never had one issue with the car. Got home from the trip, changed the aux battery and back to normal ever since. All modern cars go crazy if any battery is not up to par.
MBWorld Fanatic!
Joined: Aug 2017
Posts: 1,694
Likes: 521
2019 S560, 2015 Honda Civic Hybrid
You can also put in one of these motorcycle batteries that have similar specs:
.
As people said it can be a little fussy to change, particularly figuring out that the metal tray slides out with the battery in it. Also, the motorcycle batteries have a different terminal attachment but not too difficult to mate to the W222's wiring.
I spent a couple extra bucks and got an AGM version.
As people said it can be a little fussy to change, particularly figuring out that the metal tray slides out with the battery in it. Also, the motorcycle batteries have a different terminal attachment but not too difficult to mate to the W222's wiring.
I spent a couple extra bucks and got an AGM version.
Last edited by Tom in Austin; Sep 21, 2022 at 11:59 AM.
MBWorld Fanatic!
Joined: Jul 2013
Posts: 4,830
Likes: 772
From: Venice Florida
2018 S560
I wonder if a lithium like this battery would be ok.
I'd think something like this and you'd never have to replace the aux battery again. On my 2017 E550 the Aux batt went twice. So for on my 2018 S560 no issues yet but waiting for the message to appear one of these days as it's a real problem with these cars.
Senior Member
Joined: Jan 2020
Posts: 262
Likes: 106
W222, W221, W218, W211
I wonder if a lithium like this battery would be ok. https://www.amazon.com/dp/B091P9QXX7...NsaWNrPXRydWU= I'd think something like this and you'd never have to replace the aux battery again. On my 2017 E550 the Aux batt went twice. So for on my 2018 S560 no issues yet but waiting for the message to appear one of these days as it's a real problem with these cars.
Super Member
Joined: Jan 2009
Posts: 566
Likes: 261
From: In The Woods
2019 W222 S560 4Matic/2025 Yukon Denali
Remove the flip up floor panel 2 T20 screws
remove the rear trim panel. Two push/pull clips, then pry up to lift the panel straight up
Play safe and disconnect the neg battery term from the main battery.
View of the goal. The Aux battery is in a black plastic case that has a snap on lid. You don't remove the case, just pop off the lid
10mm nut x 2 that hold down the fuse box. You need to just move this a little to the side to gain full access
Flip up the Aux Battery cover, then unbolt the neg then pos terminal. The battery will lift out
Thanks Cosmic Trucker, did this in the parking lot of my office this am.
Took about 15 mins.
Your pics were very helpful.
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Newbie
Joined: Oct 2022
Posts: 4
Likes: 0
MB S560
2019 S560 Auxiliary Battery Malfunction
Hi,
2019, S560.
Upon start up I receive “auxiliary battery malfunction”
After a bit of research, some people are replacing their auxiliary (small) battery while others are replacing a voltage converter.
Does anyone know specifically which one the 19’ model year s560 has? Any tips/tricks for replacement is greatly appreciate!
Thank you!
2019, S560.
Upon start up I receive “auxiliary battery malfunction”
After a bit of research, some people are replacing their auxiliary (small) battery while others are replacing a voltage converter.
Does anyone know specifically which one the 19’ model year s560 has? Any tips/tricks for replacement is greatly appreciate!
Thank you!
MBWorld Fanatic!
Joined: Jul 2013
Posts: 4,830
Likes: 772
From: Venice Florida
2018 S560
Probably the same as my 2018. Battery on pass side of the trunk remove lower trunk trim and then side panel. Getting the battery in and out was tougher than I thought. Ended up taking it to an independent repair shop and they put in the new one I’d got at batteries and bulbs. 85 dollars for the battery and 100 dollars to put it in. Tried to talk them into installing it at batteries and bulbs they would not do it. Said it was more involved than replacing a regular under the hood battery. They were right.
Last edited by 2012 merc amg; May 28, 2023 at 03:07 PM.
MBWorld God!
Joined: Dec 2019
Posts: 32,222
Likes: 6,278
Hi,
2019, S560.
Upon start up I receive “auxiliary battery malfunction”
After a bit of research, some people are replacing their auxiliary (small) battery while others are replacing a voltage converter.
Does anyone know specifically which one the 19’ model year s560 has? Any tips/tricks for replacement is greatly appreciate!
Thank you!
2019, S560.
Upon start up I receive “auxiliary battery malfunction”
After a bit of research, some people are replacing their auxiliary (small) battery while others are replacing a voltage converter.
Does anyone know specifically which one the 19’ model year s560 has? Any tips/tricks for replacement is greatly appreciate!
Thank you!
Junior Member
Joined: Jan 2017
Posts: 35
Likes: 2
S350d AMG Line Premium Plus
Are Lane Assist functions affected as well as Distronic?
I've a 2017 W222 S350D UK model (RHD SWB) and for the past few months errors on start regarding Lane Assist. For the past couple of days on a trip away there have been the "Auxiliary Battery Malfunction" message and no more Distronic - which I can't do without, particularly as it helps so much with regular driving and if the vehicle in front suddenly brakes.
Thanks to all who have posted solutions and details, I'm going to give it a go to replace the battery myself.
Will this likely fix the other "auxiliary" functions that are reporting as unavailable/faulty?
Thanks to all who have posted solutions and details, I'm going to give it a go to replace the battery myself.
Will this likely fix the other "auxiliary" functions that are reporting as unavailable/faulty?
Senior Member
Joined: Jan 2019
Posts: 497
Likes: 196
From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
I've a 2017 W222 S350D UK model (RHD SWB) and for the past few months errors on start regarding Lane Assist. For the past couple of days on a trip away there have been the "Auxiliary Battery Malfunction" message and no more Distronic - which I can't do without, particularly as it helps so much with regular driving and if the vehicle in front suddenly brakes.
Thanks to all who have posted solutions and details, I'm going to give it a go to replace the battery myself.
Will this likely fix the other "auxiliary" functions that are reporting as unavailable/faulty?
Thanks to all who have posted solutions and details, I'm going to give it a go to replace the battery myself.
Will this likely fix the other "auxiliary" functions that are reporting as unavailable/faulty?
Member
Joined: Feb 2009
Posts: 212
Likes: 75
From: Tampa Bay area
S560, GLS63
Remove the flip up floor panel 2 T20 screws
remove the rear trim panel. Two push/pull clips, then pry up to lift the panel straight up
Play safe and disconnect the neg battery term from the main battery.
View of the goal. The Aux battery is in a black plastic case that has a snap on lid. You don't remove the case, just pop off the lid
10mm nut x 2 that hold down the fuse box. You need to just move this a little to the side to gain full access
Flip up the Aux Battery cover, then unbolt the neg then pos terminal. The battery will lift out
