I am happy to inform you there is finally a fix to this stop/start issue. I personally experienced this with my 2023 LZ0 and I mentioned it in the 15k Mile review video shown below. Lets get into this fix that GM just released today, 4/11/2024. #24-NA-070 Vehicle Doesn’t Restart After Coming to a Stop While in Start/Stop Mode, Malfunction Indicator Lamp (MIL) Illuminated - DTCs P138C Set.
Vehicles affected: The bulletin states LM2 2023-2024 however, the LM2 is only in the SUV's for those years, but they do list the Silverado and Sierra. I believe this was just a simple mistake and it's for all 2023-2024 3.0 Diesel vehicles.
You could just disable this system entirely, just saying.... https://youtu.be/DEVqxfxBm6A
Two symptoms may arise and those are: The vehicle does not restart after coming to a stop while in Stop-Start mode. Or, MIL illuminated with a stored code for P138C.
The cause: A software anomaly
The Fix: Reprogram the ECM to the latest available software.
Coverage - This may be at a cost to you, but may be covered under warranty - See your dealer.
Video mentioning the issue @ 14.55