l3lue2010

I got the "auxiliary battery malfunction " error on my c450 so I went and replaced the capacitor in the passenger floor panel, but the error is still there..should the error clear itself once it's replaced or do I need to get a scanner to erase the code? Or could that error be something else?

l3lue2010

Took the original one apart, wow yeah i'd say thats a malfunction LOL

gpouliniii

Mine said “Stop vehicle, leave engine running” in my C450. I changed the Voltage Converter/Auxiliary Battery like you did and I had the battery disconnected the entire time and hooked everything back up and 2 mins after I started the car back up, same message appeared. But it went away for awhile for about two weeks popping up randomly and now it’s going off more often. I’m thinking my main battery or alternator is going bad, but those usually just go bad without warning and then you replace it or it runs the main battery dead, but the car starts and runs fine every single time I drive it. Have you found out if you need to have codes wiped out or whether that matters or not yet? If I hear something, I’ll let you know as well!

gpouliniii

This is what it says when it goes off. I do have an amp and sub installed in my car, but I had a professional installer do it. It’s a JL Audio 12” with a built in 500watt amp and it all came as a package from JL Audio in one box. It might be draining the battery, but I doubt it should be throwing this code.

l3lue2010

I didn't have that same error, only thing I had was the "auxiliary battery malfunction", I haven't had a chance to drive the car around much since i've replaced it, i've read it may go away on its on own once I drive it around. Apparently from what I've read this part is used to control the eco start/stop function (which has never worked since i've owned the car - I just never gave much thought to it because I always found that annoying) but this error just popped up last week. I'll keep you posted if the error goes away or if I have to figure out a way to clear the code.

'1663s

I just got this error in my c63. I have a service appointment this Friday. Will let you guys know what they replace and whether it fixes it.

gpouliniii

Please do!

l3lue2010

I took the car for a drive last night and still same error, I'm going try to order a scanner (which I should probably have anyway) and clear the code and see if that helps.

DLAMG_1979

I recently just dealt with both of these issues.

1) First, I got the Aux Battery Malfunction light coming on. Mostly just really annoying because it pops up like every 5 seconds. Replaced the aux battery in the passenger footwell and it went away. There’s a few DIY videos on youtube. Never did anything with coding/software update, just straight up swapped it out with a new one from mercedes and the message never came back.

2) A few weeks later, I got the Stop Vehicle.. message popping up. I went on a highway drive to try and charge up the battery and it went away for a day, but came back. I am running two 12s and an Amp, so I figured my stock battery was on its way out and decided to get an Optima Yellow Top instead. Swapped it out in the Autozone parking lot and the Stop Vehicle... message never came back on. I’d bet its a bad main battery.

gpouliniii

I figured it was either the battery or the alternator. I was hoping it was the battery. Thanks for the info man!

l3lue2010

With the aux battery did you have to clear the code afterwards? I swapped mine out but still have the error. Drove it a couple times now and it keeps popping up every 5 seconds like you said...I wonder if I should take it apart an double check the connection

I will probably also swap out the main battery to a new one for good measure because it has to be close to the end of its life span

stockbmw

Did any of you with aux or battery problem, did your eco stop/start ever worked?

If you are still getting the aux error and eco stop/start don't work, and changed the aux cap module, I would check the fuse.

If eco stop/start don't work with stop the car error, it's probably the battery. I would get the battery tested at your local part store. Most does it for free.

l3lue2010

My eco start/stop never did work for the year i've owned it (honestly never even knew it was supposed to do that lol) but I also have never checked the fuse (good call)

I have never gotten the stop the error, but i've heard the car will start doing strange things as the battery starts to go bad.

DLAMG_1979

I thought we would have to clear something, but no, the MB Canada Tech who helped me in my driveway said we didn’t need to clear anything, and sure enough it never came back on after we swapped it.

Where did you get replacement part from?

'1663s

Had my service appointment yesterday. Service dept. told me the "buffer battery" needs replacement. I did not go through with it because after already having to pay a $170 diagnostic fee for any battery issue, they wanted $385 plus some other fee to replace the battery. I've had this car for 10 days so needless to say I'm going to be taking it up with the dealer who sold it to me. Will respond again when its replaced about whether the issues persists.

mau108

Man I coded my car to remember last setting related to eco/start stop(which the past year and a half its been off). Hopefully I don't run into this problem but looking at those internals and the lack of solid caps probably will run into this issue as my understanding is the car is still charging those caps/battery when you are coasting.

gpouliniii

Im getting the Stop error and it’s definitely doing some strange things. I’ve noticed that it’s been coming on more and more after I changed the auxiliary battery. Guess I need to change the main battery.

l3lue2010

Driven the car a hand full of times, still same error. Everything I've reading is that the error should go away on it's own when replaced, it was clearly bad with the popped caps. Is there anything else that could cause this error? I did order a after market one in amazon, could it be a defective part? Do I need to strictly only use OEM? I also cannot find any fuse labeled that would be for the eco start/stop on a C450, can anyone chime in with this same error?

DLAMG_1979

Did you test main battery? My guess would be its either a bad main or bad replacement aux battery you got.

gpouliniii

I changed the Aux battery/Voltage Regulator and the “Stop Vehicle Leave Engine Running” light was still there and then changed the Main Battery and it’s went off and hasn’t come back on in 5 days. And I noticed my started running better and things were working properly. These cars are very sensitive because they have so many things going at one time that the battery has to be over a certain voltage or things will stop working properly. Never seen anything like it

Holmes5518

It's the main battery causing the "stop vehicle" message, guys. And to do the job correctly, there's a battery life value that the dealership or someone with SDS needs to reset in the SAM.

netboy

i did a battery quote on AAA, it' 208$
but it' a Mercedes, i worry they might screw it up.
maybe i just call Mercedes roadside to replace the battery.

stockbmw

And who are they sending if you call mb roadside? Probably triple a

netboy

i used Mercedes roadside assistance a few years ago on 2003 C320 coupe, the guy is from my local mercedes dealer. And they only charged me for the battery, free labor / install.
how i know? the van and receipt show Mercedes of Oakland.

netboy

Mercedes is really going to the toilet !
Called Mercedes Roadside Assistance, since my warranty is expired, they charged me 75$ for roadside.
Then sent a independent contractor who has no experience with Mercedes and installed a aftermarket battery.
Good thing i read it on the internet that you need to remove the start/stop button before removing/installing battery, he never mention anything about that.
Also i heard you need to reset the battery counter on the Mercedes, he never did that either.
If i have known, i would just call AAA roadside assistance myself (i'm a member) and saved me 75$ or take the car to Mercedes dealer and installed OEM battery and reset the battery counter !