Hey,

I've recently gotten my first MB, a 2019 C220d and about a month or so ago I started experiencing a very hard kick in sport+ mode when either accelerating hard or slowing down to an intersection where sport+ downshifts from D2 to D1.
This issue does not always happen, there might be days when it doesn't happen at all, and other days it might do that multiple times in a row. I did a transmission fluid change a week ago and thought that would fix it, but just today the same issue came back.

Here's a video of the kick it does (happens at 22-second mark): , the car stops for half a second when that happens and inside the car it sounds like the transmission will explode.

So in the video you can see me "accelerating" in manual mode and the car upshifting automatically at the ~4k rpm mark to second gear, after I immediately held the right paddle shifter to switch to automatic mode (and make the car upshift to 3rd gear). After about 2 seconds of that you'll hear a loud noise and that's when the car stops for half a second. At that exact moment the car had decided to downshift from the 3rd gear into 2nd gear.

And as I mentioned, this same kick sometimes happens when I let the car roll into an intersection in sport+ mode, it happens when it downshifts from 2nd gear into 1st gear. Sport and comfort modes are fine as they'll stay in 2nd gear until I've fully stopped into an intersection.

I don't know much about cars' internals, so I would appreciate any help identifying what could be causing this issue or if something could already be broken.

 

I think it is a software issue, so I would have the dealer update or reset the transmission shift points. My older 7 speed has had all kind of weird shifting habits and every time the dealer plugs the car in, it changes. I bought the car at 34K miles and now its at almost 90K. Did service at around 60K.
I guess the dealer updates the software every time the car is in. My transmission used to bang between 1st and 2nd on downshifts (2nd to 1st) and 4th and 5th on upshifts downhill or under no load when it was newer. Later, around 40-50K something must have gotten updated and it changed for the better, only 4th to 5th was sometimes rough and generally shifting has become smoother but more delayed on downshifts/kickdown. Generally speaking it has gotten better over time.

 

Thank you for the info, relieving to hear it might just be a software issue. It's getting star-diagnosed on wednesday so hopefully they'll be able to do something to it.