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I really hope someone can possibly help me out....
Two month ago I bough a one owner C43 (Less than 50k miles on it).
I have been driving it primarily on the weekends as a "weekend car".
Every week it's been an absolute blast. No issues, great performance and of course a lot of fun.
I went on vacation for a week and recently just got back. I got in the car last weekend and it had issues starting up. (Error messages on the screen). After two tries it did start up.
Parked it for a few days and wanted to drive it again. (No chance, it will not crank....) I tried everything. Taking the key-less Go Button out and starting it with the key or disconnecting the battery.
I went ahead and bough a brand new battery yesterday and installed it (thinking this may be the issue)... Nope no change still not wanting to start.
The weird thing is that it is telling me multiple messages on the screen (Including the Aux Battery Malf.) Would the Aux Battery cause the car not to start at all? In my previous models I would still be able to start/drive it.
The other odd thing is the Anti Theft Messages that appears on the Command....
This does look like a bad battery. Many of the error messages you are getting can be caused by low voltage. A new battery needs to be coded. Did you do that? If not then the anti theft message is likely due to that because the car thinks it's been tampered with.
Thank you so much for the quick response and help.
This is the battery I installed yesterday:
Is there something special I need to do?
I know you mentioned it needs to be coded. Please explain further. I wasn’t aware something else needed to be done. Thanks!
“please note the Anti Theft Message was showing prior to me replacing the battery”.
Yes, all the electric components have so-called component protection. They are locked to the car's VIN to prevent theft, so you can't just replace them. The new component has to be registered with the on-board system. Whatever happened while you were away triggered a theft condition, so the immobilizer is currently not authorizing the engine start. You need to see a Mercedes specialist, either a dealer or a independent specialist with coding access, to clear whatever condition/fault your car has so that the immobilizer lets you start the engine and also to register the new battery. You can't do this yourself, because everything is encrypted. Only techs who pay for the certificates and are authorized can do the coding.
It’s absolutely not true that any coding needs to be completed when just changing battery. I’ve changed both the aux battery and primary over the course of my 83k miles with zero issue. If I were in your shoes, having already replaced the primary battery, I’d move on to the auxiliary since it with most likely fail eventual as well. Replaced mine June ‘21 with the link below, no issues since. If that doesn’t work, time for a trip to the shop.
It’s absolutely not true that any coding needs to be completed when just changing battery. I’ve changed both the aux battery and primary over the course of my 83k miles with zero issue. If I were in your shoes, having already replaced the primary battery, I’d move on to the auxiliary since it with most likely fail eventual as well. Replaced mine June ‘21 with the link below, no issues since. If that doesn’t work, time for a trip to the shop.
Thank you for all the replies.
I will certainly change out the Aux Battery. The link above didn't work.
Is this the one you are talking about?
Also is there any possible way the aux battery will not let the car crank? I am trying to talk myself into this may be the fix even though I am in doubt...
Usually at least on the ML W166, C W204 I was able to still drive as normal with the Aux having an issue. Unless on the W205 it is different??...
Because here comes my next question. If this doesn't fix the issue (Which I pray it does..) How the heck would I even get the car towed to the dealer? I can't even put it in gear and it's in my driveway with an incline.... lol!
This has to be an easy fix somehow.. How the heck does the car go from driving perfectly fine to not wanting to start all all overnight...!
Thank you for all the replies.
I will certainly change out the Aux Battery. The link above didn't work.
Is this the one you are talking about?
Also is there any possible way the aux battery will not let the car crank? I am trying to talk myself into this may be the fix even though I am in doubt...
Usually at least on the ML W166, C W204 I was able to still drive as normal with the Aux having an issue. Unless on the W205 it is different??...
Because here comes my next question. If this doesn't fix the issue (Which I pray it does..) How the heck would I even get the car towed to the dealer? I can't even put it in gear and it's in my driveway with an incline.... lol!
This has to be an easy fix somehow.. How the heck does the car go from driving perfectly fine to not wanting to start all all overnight...!
Thank you for everyone's help!
Image is correct, but here's the another try at the amazon link...
Edit: since you seem to have power, you should be able to pull off the start button, insert the key to the power on, then you should be able to shift in to neutral. After rewatching your video, I realized I missed the anti-theft activated prompt at the last second of the video. Just call a tow to the dealer at this point. I'll stand behind it having nothing to do with not "coding" the battery swap.
Last edited by RichardCranium3; 08-28-2023 at 05:53 PM.
Well, WIS says otherwise. Battery change has to be confirmed in the front SAM, except for the hybrid models, as the final step.
I'm not refuting what the WIS says. That said, there's no magical link between pos/neg battery terminals and MB's or any ECU in existence. If that were the case, every time you disconnect the batter for a particular service, you'd be up a creek if you didn't go through some complicated dealer-only procedure after you performed some simple trained monkey level service. Having just replaced the battery in the last 60 days in my garage in all of 4 minutes, there was, and continues to have zero inclinations such a battery swap occurred, minus the clearing of my trip computer for that particular week. My money is on a faulty or incorrect replacement battery, failing aux battery, or completely unrelated electrical gremlin.
Well, WIS says otherwise. Battery change has to be confirmed in the front SAM, except for the hybrid models, as the final step.
Confirming the battery is only to reset the recharging rate to it from the alternator. Older batteries will end up with higher recharge rates, so it's a good idea to reset it. There's something else going on with his car
On second thought, he may just need to have this reset and also the anti theft alarm reset. Maybe the low voltage from the battery triggered the anti theft system. I just saw a video that mentioned about that with another Mercedes car
https://youtu.be/4m0AGIU2zdQ?si=5T598shCI1xpR6K1
Last edited by BayAreaAMG; 08-30-2023 at 12:52 AM.
Thank you so much BayAreaAMG! You are giving me hope.... I really want to drive her again.
It would make total sense if it is something as easy as getting it reset because if I think back it all started with the Anti-Theft Alarm on the screen and went to not starting at all afterwards. This has to have some connection....
Is there any any possibly way of me resetting this? Is there a fuse to take out or anything I can do myself? I am really trying to get this fixed so bad without having to take it to a dealer...!
PFL205.064 with M276.823 (Oil pump solenoid defeated)
Originally Posted by mariusweber
Thank you so much BayAreaAMG! You are giving me hope.... I really want to drive her again.
It would make total sense if it is something as easy as getting it reset because if I think back it all started with the Anti-Theft Alarm on the screen and went to not starting at all afterwards. This has to have some connection....
Is there any any possibly way of me resetting this? Is there a fuse to take out or anything I can do myself? I am really trying to get this fixed so bad without having to take it to a dealer...!
Thank you!
If your scanner is not able to communicate with the ECU, it might be difficult to get this done yourself but there are some scanners that are capable in resetting/teaching-in the battery, but those bluetooth ones usually don't for example. You need a scanner capable in doing actuation test.
Did you measure the new battery? Perhaps the new battery came discharged before you installed it so your car is again having low voltage issues just like your old battery? How long did you disconnect the old battery for until you installed the new one, not sure if it will change anything but does disconnecting it for longer helps?
Side note, the auxiliary battery (if you take it apart) in a W205 is usually actually a capacitor.
08-27-2023, 09:51 PM
C43 Won't start all of the sudden....
