4th to 3rd downshift. I figure it's the PWM Solinoid, Pulse Width Modulator, anyone else had this problem on the 222, my car is a 2015. Hopefully the dealer will get this squared away tomorrow when I drop the car off for the A3 service as the car has 46K miles on it now and the factory warrantee expires at 50K miles. I hope they don't give ma a cannot duplicate excuse or something. When it's cold it does the abrupt 2nd to 3rd shift every time, but that abrupt 4 to 3rd shift when it's warm only happens about a couple times a month so that one is hard to duplicate. It almost feels like a car is tapping my cars rear bumper. A car as good as the S550 should not have this issue. I think replacing the PWM is only around an hour labor, drop the trans pan and it is there and put the new one on (like a 60 dollar part) and put the pan back and fill with fluid.

 

I’ve had the issue with an abrupt/harsh downshift from 5 to 4 since I bought the car brand new. Had it in twice, seemed slightly better after they flashed the transmission but then it returned to poorer form again.

Had it in for a 3rd time just a few weeks ago and they couldn’t duplicate the problem. When I returned to the dealership to show the tech the issue, even I couldn’t get it to do it. I was a absolutely CONVINCED they had fixed it and were just testing me - as I drove it for the next 10 days or so without it happening once.

Alas, the issue began recurring again with regularity, so I’ll be taking it in again. I love everything about this car except for this nuisance. A couple of others here have had the same issue.

 

Had mine in 3 times for the same issue. You can reset the transmission yourself. It will only last a month or so ( it learns how you drive to adjust the shifting accordingly ) . After they did the software update, it was better, but after a month or so, it still happens, especially when the car is cold.

 

The exact same thing happens with my 2014 S550. I have also complained to the dealer about this issue multiple times but they are not able to fix it. It's more noticeable in the winter than summer. Once the engine warms up after a few miles the transmission is nice and smooth.

 

For the most part mine is smooth. They are keeping the car overnight at the dealer to test drive it when cold tomorrow. They should notice that rough first shift from 2nd to 3rd when cold. I really think it's a flueky solenoid, probably the PWM one and I told the service advisor that. Hopefully the outcome will be good and they will get the issue squared away, if not I plan on trading this 2015 in for a 2017 within a year or so, so not the end of the world. I don't think the 17's have this issue.

 

I have noticed the same thing on my 2018 S450. On cold mornings the first time it shifts from 3rd to 4th I can feel what seems to be a very mild jolt. It's as if the transmission goes to neutral for a fraction of a second. Also noticed an occasional rough downshift at the first stop sign I come to.So after a quarter mile or so it's normal. Only happens at 50 degrees or colder. Mentioned this at the dealer the other day when I got the latest map update and of course they want to keep it overnight to test. I'll wait and see if it gets worse or not. I have 7 years of warranty remaining so not worried.

 

They simply Reflashed mine and it feels good now, hopefully it will last a while before it starts going back the other way.