Have a new 2021 Silverado 3500 Duramax w @ 8,000 miles on it. Didn't drive or start truck for several days and when I did check engine light came on. OnStar read code and it's U1345....cleared the code and it came back on when the truck was turned off and re started. Very frustrating w such new truck! Anyone had this code pop up?? Any incite would be much appreciated...thanks