I've had my 2021 Yukon Denali with the same engine for a little less than two years now and it has performed perfectly. I haven't had a single problem. I have grown nervous though because I am aware of the problems with this cylinder deactivating engine. I don't know how widespread the problem is, but I guess that doesn't matter when it happens to you. A class action lawsuit has been filed over this.
I have done a little research myself over this. The problem is collapsed lifters. This can lead to bent push rods, damaged cam shafts and possibly broken valve springs. What you can expect is GM will repair or replace that engine. The problem is that if the engine is replaced, it will be replaced with an identical engine having the same questionable lifters and the same potential problems. If they repair the engine, same thing. The lifters will be replaced with the same identical parts. So far as I know, there is no corrective action on GM's part to solve this problem, no redesigned or improved lifter. There are stories of people having their engine overhauled more than once. I'm hoping for the best but keeping my ears open for the clanking of a collapsed lifter. If it happens to me, I will have it repaired under warranty and keep the vehicle. I love driving it.
I am amazed that there are aftermarket conversion kits available called "AFM/DFM Delete Kits". These kits contain all the parts necessary to eliminate the Dynamic Fuel Management System (cylinder deactivation) and convert the engine to a standard full time V8 engine. To do this requires conventional lifters, new push rods, new camshaft, new oil pump and a few other parts. I'm sure the dealer won't do the work and I suppose it would void the warranty. You would have to find your own automotive garage to do the work and pay for it yourself. It costs around $5k. The kit with the parts around $600. This might be a good option once the GM warranty runs out. I wish GM would give us this option, even if we have to pay the additional cost.
In my opinion, when people have repairs on a new low mileage engine like this due to a widespread problem or defect, GM should grant an extended engine warranty for 150,000 miles. At least for this specific issue. Maybe this will happen due to the class action lawsuit. I wish you well.
