Last night while I was stopped to make a left turn in traffic, a message came up saying something about the the 48 volt battery. The car simultaneously shut off, and I couldn't restart it for about 20 secs. Then, the message disappeared and it started and has worked fine since. I just dropped it off at the dealer. Has anyone had a similar problem?

 

see my thread on this issue I encountered last year: https://mbworld.org/forums/cls-coupe...ssage-cel.html

 

We have the same problem here with C200 EQBoost 48V.
It prompt fault 48v indicator; and the car would sometime "confused" as in to auto start and stop when creeping at low speed during the trafic
I guess we could expect ECU software upgrade on EQBoost system? It only has like 4.6k miles on it

 

I just had my brand new GLS have the same 48V battery malfunction for the second time since i bought it. It doesn't even have 10k miles on it yet.
The first time I got the 48V battery malfunction light on and within 2 minutes the car would no longer accelerate. Mercedes said it was a manufacturing problem to do with the grounding of the 48V battery in the engine...that there was 'paint' in the way and it wasn't ground properly. They had my car for 5 days, sanded our the pain and reattached it all then said it was fine.

Less than 3 months and a few thousand miles later I had the exact same problem. Warning light comes on and then multiple other warning lights after....This time I knew to pull over right away before the engine failed. I had to have it towed in both times.
The car is BRAND new....and frankly, feels super unsafe now that this has happened twice. We will see what they say this time, it is still in the shop

 

You often wonder if these manufacturers perform sufficient BETA testing of these electronic components before they go into production. Good luck with your issue.

 

Following for an update OP, same to you Tink. I guess the wife will be glad she ignored my insistence on getting a GL450 instead of her beloved GL350...

 

So how did your issue get resolved? QUOTE=tink;8248417]I just had my brand new GLS have the same 48V battery malfunction for the second time since i bought it. It doesn't even have 10k miles on it yet.
The first time I got the 48V battery malfunction light on and within 2 minutes the car would no longer accelerate. Mercedes said it was a manufacturing problem to do with the grounding of the 48V battery in the engine...that there was 'paint' in the way and it wasn't ground properly. They had my car for 5 days, sanded our the pain and reattached it all then said it was fine.

Less than 3 months and a few thousand miles later I had the exact same problem. Warning light comes on and then multiple other warning lights after....This time I knew to pull over right away before the engine failed. I had to have it towed in both times.
The car is BRAND new....and frankly, feels super unsafe now that this has happened twice. We will see what they say this time, it is still in the shop[/QUOTE]

 

Reference bulletin LI54.10-P-069698, see attachment.

 

Bought a new E-Coupe facelift MY2021 and it broke down after just 7km while getting PPF installed (5 days after delivery). I coudln't start it up and the only message I got was the "48V battery see owner's manual" error. Towed the car to the dealership and they said the part was unavailable (the 48V battery) . I am in total disbelief. Customer Service Germany coudln't give a **** about what I had to say. As of now I have no ETA on when the car will be fixed (Car bought from europe and exported to Tunisia).
The dealer tried everything and said they never saw such a fault. Its a good to see that other people share the same problem as you and you are not alone in this.

 

Hi folks, no good update to report. When the issue happened in January, the dealer had the car for another week and said the "couldn't find the problem". I was given back the car with the promise that it won't every happen again. Fast forward to last weekend(less than 2 months after this latest event) and it happened AGAIN! This time I was going low speed and was able to pull over in a parking spot. After about 30 minutes I was able to restart the car and the warning lights were not on. I drove it slowly to the dealer which was close by and it is YET AGAIN in the dealership awaiting diagnostics.
Since this is now the 3rd time it has happened and the car has been at the dealership for week I have contact MB USA to see about the Lemon Law. I certainly can't take this brand new GLS back a 4th time and not know if the engine is going to fail on me yet again. The entire time I drive it i'm on edge not knowing if it will run or not.

This was my first MB...I bought it for the safety profile This is hilarious to me now as I've never had a more unsafe vehicle! Any advice or experience with lemon law is appreciated!

 

just posted update!

 

Just happened to me today. Car gave me the 48v battery warning and then popped another alert that said turn engine off (overheating warning) luckily I really close to home. Getting it towed in morning. I will update when I learn more.

 

So I went to Easter Vigil on Saturday evening and when I came out, my headlights were on, as well as the center interior lights. A RED warning light about the 48 Volt battery appeared on my dashboard screen. I checked and the headlight setting (which I have NEVER touched) and it was on the "Automatic" setting. I shut off my center lights, got out of my car to walk to catch a number of a house as I was calling for a tow. I came back to the car and pressed the start button again and the car started!. I went home and kept the car running for a 1/2 hour and shut it off. The lights went off. The next morning the car was fine. Two days later, a RED warning light came on to shut my vehicle down immediately as the coolant was overheating. I turned the cr off, waited a couple of minutes and the car started and the RED warning disappeared. THAT WAS IT FOR ME. I immediately drove the car to my dealership. I received a call from the dealership late yesterday and they re dropping off a vehicle to me as my vehicle will be in the shop for "awhile". I was told that the dealership would have to contact Germany as they are stumped with the issue. They know that it has to do with the 48 volt battery system but do not know how to correct. This obviously is worrisome as I purchased the vehicle for dependability. Now this.......... BTW, I own a 2020 GLS450.

 

My brand new GLC coupe got the same problem two weeks ago, the mileage is less than 2000KM, it was towed to garage. After 10 days, the dealer said they change the 48V battery and it is in good shape. Then yesterday, the warning light showed up again, the mileage is a little bit more than 3000km. I wonder how many people got the same issue. It is said Mercedes recall many models with the 48V in Japan, but I suspect they know the root cause.

 

just happened to me in my 2020 450GLS!
same thing. Warning light for 48V battery, A/C wouldn’t work and than red warning that car was overheating and shut down. It was towed to the dealer and has been there since! They still haven’t diagnosed it yet and it been 3 days!

 

Did MB charge your 48v battery or replace it with a new one? I had a similar problem and the dealer replaced the battery with a new one. So far so good. Has your problem now been resolved?

 

My ‘20 GLS had 24k miles before this happened. The dealer just told me that Mercedes instructed them now to sand all the negative grounds on the vehicle. I questioned why would it operate fine for 24k miles before this was an issue. If it was the paint on the ground connection, wouldn’t it of been an issue sooner?

 

My dealer also sanded the ground cable on my '21 E450 wagon (with 190 mies on it) but the car still wouldn't start or take a charge. They had to replace 48v battery in the end. I'm hoping that solved the problem. I was curious whether anyone who had a replacement battery continued to have issues due to battery drain, or whether the new battery did the trick.

 

MBUSA has agreed to buy back my 2020 GLS per the lemon law...after 3 shop visits for the same "48 battery malfunction". At first they gave me the same line of 'sanding down the grounds' as they said the connectivity was the issue due to paint but I had the same issues 2 more times after that. Last visit they replaced the 48 volt battery and had my car for over 2 weeks...
At this point, I can't risk being stranded in the car anymore so am giving it back. Such a bummer as I loved the car otherwise.

 

Sorry to hear you're giving it back. The replacement 48v has done it for me I think, but time will tell. You've been t!hrough too much to risk it again, I guess. Understandable. Good luck

 

Sorry that it didn't end up the way you liked, hopefully you find another car that can replace this one and have no further problems.

 

I hope the replacement will last for you as well.

 

I thought I read your post to mean that you're still driving on the replacement, and will give the MB back because you don't trust it, understandably. Did I misread you? Did you also have a replacement 48v go bad?

 

My bad buddy, sorry to confuse you. I should had explain it more clearly: I was just wishing that the replacement battery the dealership installed in your car will last and won't fail easily. So basically, I wish your repair was reliable. The 48V battery issue is pretty common, I have a friend with such problem with their CLS and another friend that had such problem with their GLE 450 , I don't personally own a CLS or a GLE 450 though so I don't personally have the problem. I hope that clears it up. Sorry for the confusion.

 

You're correct. I am driving the replacement, but I don't trust it anymore after so many failures. The new replacement battery has not failed yet, but it has only been 1 month. I can't risk another engine failure after 4 times with or without a new battery!