2018 GLS450 Jerky Transmission
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Joined: Feb 2026
Posts: 5
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2018 GLS450 Jerky Transmission
Hi all. I hope someone can help me to find the issue with my 2018 GLS450 Transmission or whatever it is.
Most of the time it has rough downshifts 4->3, 3->2, especially when coming slowly to a stop. 2->3 also hard most of the time. 3->4 is so so. Also, when slowly coming to the stop and it's already in 2nd gear just before RPMs go to IDLE speed it makes a jerk that shakes whole car (sometimes very strong, sometimes not so much, depends on conditions). That feels like another rough shift but it doesn't shift anything. Also, this kind of jerk happens when going in very slow stop and go traffic. When you almost at the stop and you press gas a bit, it makes that shake that shakes whole car back and forth. It feels like newbie on manual transmission releases clutch to quick. So, I was driving around with Xentry and monitoring lockup clutch. Whenever that shake happens the Lockup clutch engages or disengages (OPEN->SLIPPING or SLIPPING-> OPEN). There are no codes at all, and everything shows up ok in Xentry
Here what is done on the car:
- Transmission Service (few times)
- Shift Adaptations (few times)
- Replaced Torque Converter
- Replaced Valve Body
None of the above fixed anything. My friend tells me most likely that it programming thing. Transmission module was updated to whatever the latest software but zero effect
I really hope someone can bring some light on this.
Thanks
Most of the time it has rough downshifts 4->3, 3->2, especially when coming slowly to a stop. 2->3 also hard most of the time. 3->4 is so so. Also, when slowly coming to the stop and it's already in 2nd gear just before RPMs go to IDLE speed it makes a jerk that shakes whole car (sometimes very strong, sometimes not so much, depends on conditions). That feels like another rough shift but it doesn't shift anything. Also, this kind of jerk happens when going in very slow stop and go traffic. When you almost at the stop and you press gas a bit, it makes that shake that shakes whole car back and forth. It feels like newbie on manual transmission releases clutch to quick. So, I was driving around with Xentry and monitoring lockup clutch. Whenever that shake happens the Lockup clutch engages or disengages (OPEN->SLIPPING or SLIPPING-> OPEN). There are no codes at all, and everything shows up ok in Xentry
Here what is done on the car:
- Transmission Service (few times)
- Shift Adaptations (few times)
- Replaced Torque Converter
- Replaced Valve Body
None of the above fixed anything. My friend tells me most likely that it programming thing. Transmission module was updated to whatever the latest software but zero effect
I really hope someone can bring some light on this.
Thanks
Super Member
Joined: Sep 2014
Posts: 851
Likes: 113
From: NYC
18 E63S
Same exact issue I have in stop and go traffic.
No codes .
Mercedes dealer found no issues.
Transmission service done at dealer.
Here is the kicker the loaner they gave us to use while my GLS WAS SERVICED was a brand new 2026 GLC.with 500 miles only. drove exactly the same way in stop and go traffic as my GLS.
Unbelievable.
I highly suspect it's a software issue.
No codes .
Mercedes dealer found no issues.
Transmission service done at dealer.
Here is the kicker the loaner they gave us to use while my GLS WAS SERVICED was a brand new 2026 GLC.with 500 miles only. drove exactly the same way in stop and go traffic as my GLS.
Unbelievable.
I highly suspect it's a software issue.
Thread Starter
Newbie
Joined: Feb 2026
Posts: 5
Likes: 1
