2014 W222 Auxiliary Battery Malfunction (Warranty just finished)
Thread Starter
Newbie
Joined: May 2018
Posts: 2
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W222 S350 CDI
2014 W222 Auxiliary Battery Malfunction (Warranty just finished)
Warranty just finished 4 months ago, car is not driven much at all and has been parked up for a while.
Now I get the "auxiliary battery malfunction" message, Start/Stop, Distronic and the A/C do not work.
Contacted dealers, who said it can be fixed by a software update? Was not sure if this would be chargeable? Surely a software issue is manufacturing defect?
Anyone else had this fixed via a software update or does the battery need rechargin/replacing?
Now I get the "auxiliary battery malfunction" message, Start/Stop, Distronic and the A/C do not work.
Contacted dealers, who said it can be fixed by a software update? Was not sure if this would be chargeable? Surely a software issue is manufacturing defect?
Anyone else had this fixed via a software update or does the battery need rechargin/replacing?
Last edited by zedraz; May 29, 2018 at 07:20 AM.
Senior Member
Joined: Jan 2017
Posts: 485
Likes: 74
From: Marina Del Rey, CA
2015 MBZ S 550
Warranty just finished 4 months ago, car is not driven much at all and has been parked up for a while.
Now I get the "auxiliary battery malfunction" message, Start/Stop, Distronic and the A/C do not work.
Contacted dealers, who said it can be fixed by a software update? Was not sure if this would be chargeable? Surely a software issue is manufacturing defect?
Anyone else had this fixed via a software update or does the battery need rechargin/replacing?
Now I get the "auxiliary battery malfunction" message, Start/Stop, Distronic and the A/C do not work.
Contacted dealers, who said it can be fixed by a software update? Was not sure if this would be chargeable? Surely a software issue is manufacturing defect?
Anyone else had this fixed via a software update or does the battery need rechargin/replacing?
Thread Starter
Newbie
Joined: May 2018
Posts: 2
Likes: 0
W222 S350 CDI
Thanks for that guys.
Went into the dealers who wanted to run a diagnostic on it costing £110, if it was the battery that needs replacing then another £298.
Walked right out.
Driving back home, all of a sudden the start/stop started working again?! I guess it just needs a good charge? Or is it a case of once the battery dies its not going to hold the charge?
Not worked after than though, driven it a few times.
Went into the dealers who wanted to run a diagnostic on it costing £110, if it was the battery that needs replacing then another £298.
Walked right out.
Driving back home, all of a sudden the start/stop started working again?! I guess it just needs a good charge? Or is it a case of once the battery dies its not going to hold the charge?
Not worked after than though, driven it a few times.
Senior Member
Joined: Jan 2017
Posts: 485
Likes: 74
From: Marina Del Rey, CA
2015 MBZ S 550
Thanks for that guys.
Went into the dealers who wanted to run a diagnostic on it costing £110, if it was the battery that needs replacing then another £298.
Walked right out.
Driving back home, all of a sudden the start/stop started working again?! I guess it just needs a good charge? Or is it a case of once the battery dies its not going to hold the charge?
Not worked after than though, driven it a few times.
Went into the dealers who wanted to run a diagnostic on it costing £110, if it was the battery that needs replacing then another £298.
Walked right out.
Driving back home, all of a sudden the start/stop started working again?! I guess it just needs a good charge? Or is it a case of once the battery dies its not going to hold the charge?
Not worked after than though, driven it a few times.
Super Member
Joined: May 2014
Posts: 620
Likes: 65
From: Florida
2018 E300 Luxury - P3 and more
I went through THREE (!) Aux batteries in my 2015 W212 in the time I had it.
As to why they failed, I never got to examine the batteries nor put a meter on the system, BUT my theory is the battery's too small for the loads they're asking it to carry, so it's getting cycled rapidly.
As to why they failed, I never got to examine the batteries nor put a meter on the system, BUT my theory is the battery's too small for the loads they're asking it to carry, so it's getting cycled rapidly.
Senior Member
Joined: Mar 2018
Posts: 493
Likes: 182
2006 W221 S500L M273
This usually happens to cars that don't drive a lot or only short journeys.
If that's you, keep it on a charger (CTEK is a good brand for chargers).
If your Merc has 2 (or 3) lead-acid batteries, only charge the aux battery in the trunk.
If that's you, keep it on a charger (CTEK is a good brand for chargers).
If your Merc has 2 (or 3) lead-acid batteries, only charge the aux battery in the trunk.
