Beer Belly

I will let him know to give that a try, not sure the CEL stays on long enough, he sez it only last a minute or so. Thanks

My Nephew has a 2021 Denali he bought used from a GM dealership I have an extremely good rapport with. He had an issue with his truck where the dash lit up like a Christmas tree and had a rough idle. I called those I know in the dealership service department and alerted them that "My Nephew is bringing in his truck with what sounds like the infamous Lifter issue". He brought it in and they first found two faulty Injectors, and still not running quite right, then went for the Lifters. I'm not happy with them going for the Injectors first (which are out of warranty), had a talk with them and they gave him very deep discount. Anyhow, since getting the truck back, he has an intermittent check engine light, truck runs rough, then light goes out and truck is fine, never lasts for a long period of time. He brought it back to the dealership, they have had the truck twice now, put 100+ miles on it and say they cannot replicate, my Nephew drives off and within 20 miles, experiences to problem. I've suggested they check for bad grounds, not sure what they have checked, I just feel they are ignoring the issue. I told my Nephew keep driving till you get a steady light or it blows up....can't fix it if it's not broke. Any ideas WTF is going on ?......does GM have a diagnostic tool that they could hook up and takes a picture of sensor readings 30 seconds before a CEL and during the CEL, to give the tech an idea of what is failing ?

My first thought was a clogged A/C drain line

I went with Billstiens on all four corners, Spring Base from old front shocks would not come off to be transferred, had to purchase these new front shocks just for the spring base for the Billstiens (not happy). Now I'm left with new, OEM Shocks, minus spring base, cost $600, willing to sell locally for $400 OBO. Danbury Connecticut area.

Seems like you've done all the items I've heard about. I got lucky, and quick swap with a new Brake Controller and done. Keep us up do date with what you find, may help others. TIA

I saw a You Tube video stating GM has lost a Lawsuit concerning the damages caused by the AFM/DOD System that GM has known to damage Lifters / Push Rods / Camshaft and engine failures......any truth to this ?

My '15 Sierra early on had a misfire cyl 7.....ended up being Lifter issue, replaced the entire bank under warranty

Sounds a bit like what I had with my truck.....more of a creaking than a bump sound. I sprayed the snot out of the control arm bushings with PB Blaster, seemed to work for my situation

I'm looking at hooking up Aux also, I want to control them from the Bed Lights, isn't there Block somewhere under the bed where I can tap in ?. I want to use the lights when needed, don't want them coming on when I lock the truck at night at the campground and disturbing fellow campers.

If you just want to clean off the "junk", make a paste with Baking Soda, let it sit, may need to use a toothbrush to scub a bit, then rinse with water. Again, this is just to clean the junk, best to do as diyer2 suggest to avoid problems.

2015 GMC Sierra, 66,500 miles, had a bank of Lifters replaced at about 27k, A/C Condensor recently, other than that, I absolutley love this truck, and believe me when I say I work this truck, it does not get babied by any means.

I have not heard of anything. I have great rapport with my dealer, they replaced the Condenser for $344, originally quoted $1,200. Have a talk with your service manager.

On my 2006, 93,000 miles, right after the Front Diff and Tranfer Case the month before. The Wheek Bearing also took out Axle Seals and Rotors the wheel was so cocked. My '15 Sierra has just hit 64,000 miles, so far we are good.

My dealer diagnosed the Brake Controller in the dash. Bought from Rock Auto and replaced myself in 15 minutes, seems to be fine now