3.0 Duramax Shudder?

[smokey4266]

2021 sierra 1500 3.0 10-speed.  Mid July 2024 (63k miles) experienced random shifting in and out of gears at approxately 65 mph.  Pulled over, turned off and back on, made it to destination and no problems after.  Next day same issue.  One time it shifted into a gear so low that the tires chirped and it felt like I hit something. Dealer thought was valve body and due to back order, replaced the entire tranny.  Got truck back and 2 days later problem repeated.  I had dealer tow it this time due to my safety concerns.  20 days later I'm told by dealer that problems is def tank temp sensor. I asked how a def tank anything would affect shifting and was told that if that sensor goes bad it affects alot of other systems. Anybody experience this issue and a def tank temp sensor replacement fix the problem??

Edited August 29, 2024 by smokey4266

[Cody209]

On 1/20/2023 at 7:19 AM, bilge pump said:

I had exactly what others have described with the shudder while accelerating.

took several trips to the dealer (they were great.  stuck with it) over about 9 months but seem to have gotten it fixed.

 

Mine is a '22.  service manager told me there was a TSB on '21 models to change the transmission valve train.

replace the one in my truck and I haven't been able to recreate the vibration.  

You have the TSB number? Thanks 

[Spk15]

Have 2022 Sierra 1500 AT4 refresh, having some sort of shudder between 70-85mph. Only does it with like 50% accel. Only does it in that speed range, can give full accel anytime before that and has no problem. Manual shift through gears, no problem. Just within that range. Any help?