wanted to add another experience with this. I just took my 2014 6.2L into the dealer to have them look into a loud ticking sound. turns out the #4 AFM lifter rod was bent. they are recommending replacing the rod/lifter for all 4 cylinders on that side of the engine. Truck only has 55k miles on it, but I have had it for over 5 years...so out of warranty. Dealer actually contacted GM and they are agreeing to pay for the bulk of the cost. they will not say that the AFM caused this, and I don't have any facts to back that up. I am impressed that GM would cover most of it out of warranty. given the low mileage, I think they should. I also have been dealing with this particular dealer for a while, and they are truly one of the best.