2021 GMC Sierra Problems: Transmission, Engine and Electrical Defects Explained Joshua ValeroMay 10, 20262021 GMC Sierra problems, GMC Sierra transmission problems, GMC Sierra lifter failure, 2021 Sierra engine issues, GMC Sierra lemon law, GM transmission defect, GMC Sierra electrical problems, California lemon law GMC Sierra, 6.2L engine problems GM, GMC Sierra buyback, GM truck transmission lawsuit, GMC Sierra repair issues