nickchodge

Same exact issue. Bought my Sierra AT4 in May. It has already been in the shop more than 30 days for this issue. Same thing with part not being available. Ultimately, the replaced the entire catalytic converter after going back and forth with Detroit. I requested replacement of the truck, but GMC would not do it on the same loan terms I have (0% interest). After reading this thread, I don't want a replacement now anyway. I am pursuing Lemon Law in Washington state and will request a buyback of the truck. GMC Customer Care and the dealership (George Gee, Spokane) were no help at all. Really a shame for the price.

I had this same problem with my 2020 AT4 3.0 diesel. Picked up in June. At 1900 miles the check engine light came on. Took it to dealer and they said the same thing: this is something new and they had to contact GM headquarters for info. I was told it was a diesel particulate sensor. They've had my truck 7 days. Am supposed to get it back today. I am in Spokane, WA.