2021 Tahoe Premier Transmission

[Ceddibear]

Yes my wife was driving once and had that same transmission code thrown. Took it to a decent mechanic who found nothing wrong issues. Month later a flurry of codes were thrown and she couldn’t even brake and went into a panic. Eventually she was able to stop without damage and after all the diagnosis it ended up being a bad battery.

 

[Micahsd]

I know it sounds crazy. But check your battery. If it's the original, and is going bad it will throw all sorts of warnings, because the computers do not like low voltage.

Had a similar issue in my 2021, just recently. It had the original battery from 4/8/2020.

Here's a how to:

Excellent video! Very detailed.
Might have to use it on my ‘21 as its battery is starting to get up there in age. Thanks!