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Dropped mine off today. I initially got some static from the service person, saying a ‘battery’ is not covered under warranty or extended warranty. I reminder her that on the W205, it’s a capacitor. She checked with the manager or someone, and sounds like it will be covered.
I also have a tear in my drivers seat pan at the stitching. A 2015 with <50k miles, unbelievable. Waiting for their response, warranty coverage is at discretion of the dealer, apparently.
My eco has stopped working on a 2016 c250d. The display show the yellow circle A with a line through it. It is switched on. Am I right in thinking the the display showing mph and another which goes green and says charge has to do with charging the battery to power eco. This charge graph only goes green sometimes mostly sits in white as if not charging.
Hi Norman, did you manage to solve this problem? I have the same problem in my 2016 C220 and it's not exactly clear in any of the information I have researched that the converter is actually the problem.
I have only recently bought the car and I'm beginning to wonder why as there seems to be inherent problems with it!
Thank you in anticipation..Jon
Just got my 2015 C300 fixed for this issue today. Luckily, all was covered under extended warranty...otherwise it would cost usd 500 to repair. I'm impressed to see how many users are experiencing this.
Is it supposedly to be replaced at a certain mileage? I couldn't find it anywhere.
i have a 2014 S550 I CANT FIND MY CONVERTER ITS NOT IN THAT PLACE U HELPED THAT PERSON ?
The voltage converter in the C class replaces the auxiliary battery in your car. You don't have a converter. You have two batteries in your trunk. Here are some documents on replacing the aux battery: https://mercedesforum.com/forum/merc...15-s550-58710/
I have just been to MB dealer to do an MOT on (w205 Cclass 220d amg line - yr 2015) and resolve the error "auxiliary battery malfunction". I was happy the car passed the MOT, but very disappointed the battery fix (replace aux battery capacitor) was not covered by my used car MB Comprehensive Warranty. The MB dealer wanted to charge £475 inc tax. I decided not to carry out the repair due to the cost and I simply don't use the car every day and this issue does not impact driving, The weird (i'm not complaining!) thing is when my car was handed back to me after the MOT, the battery error disappeared. So I am wondering if any of you have been to the MB dealer and they did a software update/fix (possible after an MOT??) or did a kind of reset to stop this error when the aux battery is working fine. My start/stop even worked on the way home. Or should I be concerned this issue will surface again soon when the car will self diagnose a aux battery malfunction. From my experience the issue started when I did not drive the car after a few days during the winter months. Any advice is welcome.
I have just been to MB dealer to do an MOT on (w205 Cclass 220d amg line - yr 2015) and resolve the error "auxiliary battery malfunction". I was happy the car passed the MOT, but very disappointed the battery fix (replace aux battery capacitor) was not covered by my used car MB Comprehensive Warranty. The MB dealer wanted to charge £475 inc tax. I decided not to carry out the repair due to the cost and I simply don't use the car every day and this issue does not impact driving, The weird (i'm not complaining!) thing is when my car was handed back to me after the MOT, the battery error disappeared. So I am wondering if any of you have been to the MB dealer and they did a software update/fix (possible after an MOT??) or did a kind of reset to stop this error when the aux battery is working fine. My start/stop even worked on the way home. Or should I be concerned this issue will surface again soon when the car will self diagnose a aux battery malfunction. From my experience the issue started when I did not drive the car after a few days during the winter months. Any advice is welcome.
Thanks Snoop
If you don't care for eco stop/start, remove the wire for the function from the battery. There is a clip on negative terminal. I expected aux battery error or some other message but so far so good after a month. Engine idles 200 rpm more then before, but I am okay with that for now.
. Took me half an hour to replace. Ordered spare part on AliExpress. Refurbished for € 45,-.
It seems this is a very weak part, which is always the case with capacities. They tend to leak and damage the circuit board, as did with mine:
Hello. I own 2015 c250 and "stop the vehicle, shift to P, leave engine running" popped twice. I shut down the engine and restart it and it disappears.
Someone can help me please and what could be the problem? thanks
Hello. I own 2015 c250 and "stop the vehicle, shift to P, leave engine running" popped twice. I shut down the engine and restart it and it disappears.
Someone can help me please and what could be the problem? thanks
So I get the message Auxiliary battery malfunction in white on the dash. I changed the part the next day with unit from MB but after changing it the message still appears.
Eco mode isn’t working so now I’m wondering if the unit from the dealer is bad.
I’m also trying to figure out if I needed to clear the message with a scanner
So I get the message Auxiliary battery malfunction in white on the dash. I changed the part the next day with unit from MB but after changing it the message still appears.
Eco mode isn’t working so now I’m wondering if the unit from the dealer is bad.
I’m also trying to figure out if I needed to clear the message with a scanner
It definitely is a job to tackle on your own.
my experience is this I replaced my main battery at a cost of £200+ but my son who has an slk charged my old battery and replaced his with mine (identical fitment ) he was having probs. That was in January it hasn’t coughed since. I rest my case .......
my experience is this I replaced my main battery at a cost of £200+ but my son who has an slk charged my old battery and replaced his with mine (identical fitment ) he was having probs. That was in January it hasn’t coughed since. I rest my case .......
Oh forgot to add replacing the main battery cured the problem. I’ve had eco stop start ever since
After I replaced the capacitor/aux battery I couldn't start the engine and had to call the roadside assist but I attempted this DIY project after the car had been parked for over 3-4 weeks. The roadside assist guy assessed the health of the battery and it was to my surprise still good after almost 6 years.
Got the "auxiliary battery malfunction" message flashing on my dashboard on Monday. Used this forum to work out the problem and picked up a part from my local MB garage this morning. Decided I'd rather put genuine parts in just in case. A 205 905 34 14 80 is the MB part number. £106 for the part from MB or £45 for a Chinese version off eBay. Decided my C63 was not worth the risk of £60.
Completed the change over in less than half an hour. Really simple. Biggest problem was getting my fat head into the small area.
Gave the car a quick drive round the block and message has disappeared. Thanks everyone on this forum for your help!
I changed the auxiliary battery about 2-3 yrs ago myself on my 2015 C300. Is there a lifespan of this part? Has anyone replaced more than once? Does it need replacement every 3 yrs or so? Last time I had an Auxillary Battery Malfunction message on the dashboard but now I am having an issue on restarting from an ECO Start Stop engine shutoff. Some are saying the auxiliary battery can be bad without an error message?
My understanding of the component failure were poor capacitors within the so called aux battery, It can cause the stop start function to stop working ie the engine will keep running when the vehicle stops, I doubt it would cause the engine to not start
My understanding of the component failure were poor capacitors within the so called aux battery, It can cause the stop start function to stop working ie the engine will keep running when the vehicle stops, I doubt it would cause the engine to not start
That is what I had the first time but that was almost better since the start / stop would be disabled. For some reason now the start / stop is essentially stalling after a STOP. You can restart the car by placing into P or N. That is why I was wondering if people have seen failures without any dashboard lights/warnings and if this part has a life expectancy. Maybe some intermittent failure. It is around $50-100, if there is a high likelihood of a repeat failure after 3 yrs, I could just replace it rather than spending 2-3 times that to have the dealer diagnose that and then more to fix it.
That doesn't really sound like a problem with the voltage converter, it's only used to keep things like your multimedia screen, fans etc. running.
Engine still cranks from main battery, maybe that one is on the way out without the car realising it (it shouldn't let you auto stop with a weak main battery).
Maybe get the car to somebody with STAR so they can carry out proper diagnostics as armchairing here wouldn't do too much good.
I seem to remember others having the problem of the engine not restarting at the lights etc and having to select neutral to restart, this was several years back, maybe a search will locate it. I understand your reluctance to go to a dealer to diagnose the fault
10-24-2019, 06:53 PM
Wooooo saaaaaa!! 
but I attempted this DIY project after the car had been parked for over 3-4 weeks. The roadside assist guy assessed the health of the battery and it was to my surprise still good after almost 6 years.
