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Well, just to help anyone else out with a current 2025 story of GM lifter failure.... My 2015 Silverado 1500 LTZ with 35k miles on the 5.3L L83 (carefully maintained) experienced the telltale lifter tick on the passenger side (either cyl no. 4 or 6) with hesitation under load and I had it brought (towed) to the dealership. Cylinder #6 lifter failure. Dealer quoted $4,680 to repair based on TSB 15-06-01-002H. If the camshaft was found also damaged, the bill goes to over $9000. "But you're getting a 2-year warranty with unlimited mileage!" they told me. Yeah, great. The 6-year powertrain warranty did me a lot of good (I don't think it was ever used). I've contacted corporate customer care along the way. Now I get to see what they have to say for all this, as I find this an absolutely unacceptable burden... and $9k+ is litigation territory in my humble opinion. This isn't just abuse or bad luck, we all know this is a full-blown design defect. So how's that class-action lawsuit coming along, gents?

A few weeks ago, while driving my 2011 GMC Yukon Denali (with 185,000 miles), the vehicle suddenly began making an obnoxious noise. There were no check engine lights, but the engine sounded rough. I later discovered that it was an AFM (Active Fuel Management) lifter failure on Cylinder 6. I was able to drive the vehicle home, and based on recommendations to avoid further damage, I parked it and began researching the issue. With the help of a friend, I started diagnosing the problem. The first step was to confirm lifter failure by removing the valve cover. We identified the issue on the exhaust valve of Cylinder 6 its rocker arm was barely moving, indicating a lifter problem. I tried the Marvel Mystery Oil method, following instructions to let the engine idle and drive it briefly, but after several attempts, it didn’t help. I realized that continuing to run the engine in this condition could cause more serious damage, so I decided to move forward with a proper repair. That meant rebuilding the head and replacing the lifters with new ones. I proceeded with head removal steps by taking out the exhaust, intake, and finally the head where the problem was present. After removing the head and removing the lifter trays i laid out the lifters and confirmed one of them was soo stuck that it prevented the roller from moving: I decided to proceed with using the AFM (Active Fuel Management) version of the lifters to repair the issue. I wasn’t entirely sure what kind of emissions or smog-related problems I might run into with California regulations during the next registration cycle, so I chose the path of least resistance and stuck with the original AFM setup. The repair involved the following: 4 brand-new OEM AFM lifters 4 new standard lifters New head gasket New exhaust gasket and bolts New head bolts New valve cover gasket New valve stem seals Cylinder head machined (0.004” taken off) and deep cleaned New dowel pins for head alignment New lifter guide trays New valley cover (valve lifter oil manifold) with new solenoids New oil pressure sensor Fuel injectors cleaned, flow-tested for spray pattern and resistance, with new O-rings installed New intake manifold gasket New ignition coils, coil wires, and spark plugs All components were properly torqued according to specifications, including the head bolts which were torqued in three stages. Now after all that I am getting the consistent Misfire on Cylinder 6, this is the Cylinder that had the original Lifter failure: I tested the ignition coils and fuel injectors which are working as expected. I did compression test of the newly installed head getting the following readings (around ~180 for all 4 cylinders on rebuilt head): I was told that if the cylinder head wasn’t installed correctly, I wouldn’t get proper compression. At this point, I’m not sure what the root issue could be. The only thing that comes to mind is a possible problem with the wiring harness for the ignition coils or fuel injectors but that seems unlikely and a bit strange. Has anyone experienced something similar or have any ideas on what the issue might be, given everything I’ve done so far? If I can’t get this resolved, my next step will likely be a full rebuild and an AFM delete I'm ready to get rid of that system entirely and make this engine truly reliable again. Thanks in advance for any help or input!

I have a 2017 Sierra with a 5.3. I have had free oil changes for the last two years and have used the dealer's supplied Dexos. My engine and transmission are working great. I have read that many people hare having issues with AFM and hard shifting trannies. I have use Amsiol signature in all my other vehicles. Has any one switched to Amsoil and experienced problems? I am wondering if I should leave well enough alone.

We have a 2016 Yukon 6.2L which developed a rattle at approximately 60k miles. Initially I believed the source of the rattle was a heat shield, but everything seems to be tight. It has been to the dealer twice and no progress has been made to resolve the issue. The first time they dismissed the problem and called it "normal" and the second time they believe it's a broken baffle weld in the muffler. What do you think? Thanks in advance Video with several angles from under the vehicle demonstrating the issue. The problem only surfaces when the vehicle inters v4 mode. Also, the rattle is so loud it is picked up by the Knock Sensors and it pulling timing. Scan performed with HP Tuners VCM Scanner.

Hello, 2012 Silverado 4X4 Ext Cab LC9 with 101k miles. As the title states, I have a unique situation. The cab and bed are entirely off of my truck (T-bone damage), thus I thought this would be a good time to do a DOD delete as well as any other recommended upgrades or repairs WHILE THE CAB AND BED ARE OFF! I haven't looked at too many kits yet (Scoggin Dickeys, Texas Speed, WS6Store, etc) and still figuring what I need/don't need. Definitely would like to put in a mild performance cam if it isn't too much extra. I'm new to these trucks, so I don't know all the weak spots other than the DOD system. Basically, I'm interested in bulletproofing the system much like 6.0 powerstroke owners had to do. I just heard about the oil pickup o-ring. WTH! Wow GM.... Worth it to do this at the same time as the DOD probably. Something about a AFM plate in the oil pan? But I'm open to your input. What else? something about timing chain guides??? I vaguely remember something about a fuel system issue being pretty common as well? Sorry if I am all over the place. SO many questions right now. I just got the cab off yesterday and pretty much planning on ordering what I need by the end of this week Be doing all the work myself Thanks!

Hey Guys, I have a 2010 Chevrolet Tahoe PPV with a 5.3L LMG and a 6L80 Trans (MYC) looking to drop in a 6.2L L9H. As far as I understand it is a direct swap. Would I run in to any issues or codes as far as the L9H not having AFM/DOD? I plan on using the 5.3L PCM and having it re flashed to work with the 6.2 Or do I look for a L94 that has FlexFuel, VVT, AFM like the LMG does?

Does anyone know if the AFM problems were solved? Should I be concerned with the AFM in my new 2016 5.3L Silverado? thanks!

I don't know much about this system, how it operates, the stress that is placed on the lifters during cylinder deactivation. How common is this failure? Been watching some YouTube videos on the repair and it's very labor intensive...heads have to come off, etc. I see that you can buy the entire kit (lifters, gaskets) for around $500. Have a friend that told me...just change your oil, you'll be fine. The number one cause of this failure is neglected maintenance. That true? Or is it an inherited problem with the design of the system? The system came out in 2007, there must be some improvements made to it since then, no? I must say that the AFM is allowing me to get some excellent fuel economy out of a full size truck. So is this a common problem, or are there people with 200,000 on these trucks that never had an issue with it?

Thought I’d share what’s going on with my 2012 6.2L Yukon XL. Warning its long, but perhaps it will help someone with the same issues. The short & sweet: L94 6.2 AFM motor with cold start noise. Lifters were replaced prior to our purchase about 9 months ago, and this week my dealer replaced the camshaft & lifters noted camshaft damage. Videos of noise before and after below. There is still a noise after the repair, piston slap - and would you say normal? The detailed story. Purchased 9 months ago in North Alabama. 2012 Yukon XL Denali 6.2L (L94 with AFM) AWD. 1 Owner, 89,897 miles. Apparently at 89,741 (2 months prior to purchase) the lifters were replaced under powertrain warranty, no evidence the camshaft was replaced at that time. I purchased it without that information provided. But no problem, it was running smooth at the time, warm spring Alabama temps. My dad works in parts so had a friend pull the RPO codes & transaction history for the truck, thats how I found out about the lifter work. I did a clean up oil change right after purchase then swapped to my AMSOIL batch on hand. Fast forward to November 2015 timeframe. The nights are getting cooler, and I start to notice the noise at cold starts. The noise disappears once the motor warmed up, and I mean FULLY warmed up. It would clatter for 15 miles to town. I started researching and found TSB & lots of reports of lifter noise, piston slap common with these motors. I honestly wasn’t sure which it was so I laid out my plan to try and eliminate the lifter noise possibility since it was just repaired. From the start of November I completed 3 oil/filter changes. I downgraded from my AMSOIL filters and oil to ACDELCO filters and whatever Dexos oil I could get my hands on. I removed the intake manifold and did a good cleaning of the manifold and intake valves (added a nice catch can as well). I replaced the oil pressure sending unit and the little filter (it was clean but had to check). I removed the valve covers and removed each rocker, cleaned each pushrod with a pushrod brush & B12. I then sprayed a little B12 through each pushrod onto the lifters. Then poured fresh oil over the rockers to prevent dry start. All looked good internally from the get go. After the cleaning & immediate oil change the first start up sounded good! I honestly thought some contaminates just got in the lifters and the cleaning helped. In hindsight the temp was around 60 so the sound was probably just muted. The next day a cold morning, the noise was back. Now even more of a shrill at times with any acceleration. The holidays hit and delayed my trip to the dealer. So last Tuesday I dropped it off at the dealer with 97100 miles. I simply told the service lady it had a bad cold start noise with a prior history of motor work before our purchase & to please have it left outside overnight for a cold am start. The next day she called to say the mechanic has ordered a camshaft & is trying to find out from the previous dealer if the camshaft was ever replaced. Would take a week to repair under powertrain. I had him replace the oil pump & water pump while he was doing the surgery at no extra labor cost. Picked the truck up last night. The mechanic stated he could not find any evidence that the prior dealer replaced the camshaft only the lifters at 89,741. So he replaced both the camshaft & all lifters again. Stated he did find camshaft damage & not sure if it occurred before my purchase or not since it wasn't replaced. He said the motor internally looked real good for one of this millage & the pistons were rather clean (he speculated they had carbon knocked off during its last tear down). So now, the next morning, the temp is 30 outside. I start it up and it has a similar noise to what I brought it in for. It still continues to tap for a good 15 min of driving. Piston slap? I'm hoping this is just the normal noise & we can go on for another 10 years with no major tear downs. Please set my mind at ease. Thanks!

Hi everyone- brand new to the forum. Thought I'd throw out a question about my 2008 Chevy Suburban LTZ sitting in the shop right now waiting on a replacement GM-cert refurb engine. Should be put in in the next several days. Truck has 165K miles. Started chewing oil back in 2012 at around 80K. Was in shop 3 times in 2013 with the usual AFM issues up until the 110K mile mark when the 3rd operation was done (I think it was replacement of all pistons). All-told, about $7250 of warranty work done to truck related to AFM. Soooooo, truck recently had misfiring on cylinder 5, low oil pressure warning, drop of pressure, left on side of road. Towed to dealership. Engine not holding pressure, needs new engine. I expect the engine to have 3 yrs/100K warranty. My question is this: Should I disable the AFM with the "Range AFM Disabler" (http://www.rangetechnology.com/products/range-v8) device on this 'new' engine to (likely) eliminate any potential issues, or should I trust the newer version of this engine that was ordered will behave and perform as desired. I am also a bit confused about posts discussing 'deleting' the AFM with "kits" or having to put different parts into the engine to turn AFM off, while getting normal, expected behavior from the engine. Thank you all for any feedback. Love this forum! John

My 2008 5.3L 4WD Avalanche with ~135K miles has recently been throwing a P0306 cylinder 6 misfire, along with a Stablitrak warning. It first happened a couple weeks ago but only lasted a day. I cleared the code and it was fine for another couple of weeks before it happened again today. It does go through a lot of oil (probably a at every 1,000 miles), and there is a clicking sound. I know from researching this the last couple weeks that its likely failure of the #6 cylinder lifter and/or plug fouling due to the AFM system design and/or old PCV cover. I intend on doing some diagnostics this weekend including inspecting and replacing (if needed) plugs/wires/coils, doing compression tests, and pulling off valve covers to look for stuck lifters/valves. My questions are: 1) Other than the obvious, is there anything else I should be specifically looking out for when running these tests? 2) Are there are any other diagnostic tests I should be doing while I am in there. 3) Assuming compression test is fine, and replacing plugs/wires stops the misfires, can I hold off on replacing a bad lifter if there is one? 4) I would plan on getting a Range tuner to disable AFM (which I should have done when I bought the truck 3 years ago) and replacing the valve coverwith the new one. If the compression test is OK suggesting there is (currently) no ring, gasket, valve, etc. damage, would these measures stave off more issues? 4) If a lifter is bad and I really need to replace it now, can I just replace the one, or do I need to replace them all? Also, how difficult is it to take the passenger side head off to access the #6 lifters? 5) If it does fail compression, am I likely screwed and looking at a rebuild or replacement? 6) Any other advice, recommendations, or thoughts? Thanks in advance!

So I have searched Google a ton, with no luck. I am curious: has anyone tried to tune their truck in such a way to get the AFM to engage more often? There's tons of solutions for a full AFM delete. I wanna know if it's possible to go the opposite way; and increase the tolerances on whatever parameters the ECU monitors (engine loading, throttle position, etc...) To trigger V4 mode? I don't have a great need to actually do this....I'm more curious than anything....

Looking at crew cab short bed 4x4’s with the V8’s. I just can’t wrap my head around not having low range so it’ll either be a Z71 or a Trail Boss. Been watching prices and I’m seeing Custom Trail Boss trucks starting to get close to the prices of the LT. As in within a grand or even less. Anyone bought a Custom and regret it? I have a 2011 Silverado 1500 4x4 and my wife has a 2017 Yukon 4x4. Both have the 6L80 transmission and hers has the Ecotec 5.3 V8. Very happy with that engine and transmission combo and even with less power my ‘11 moves and drives well with the 3.42 gears. Will I miss anything with a Custom instead of a regular LT Z71? 6 spd vs 8 spd? Gas mileage? Something else?

Hey all. So, my father's 2017 Silverado (base level cluster) shows if the truck is in 8 cyl or 4 cyl AFM mode in the DIC. However, I cannot seem to find any way to tell what AFM mode I am in on my 2020 Sierra 1500 with the base level cluster/DIC. Does anyone have any clue how you can tell what mode the truck is running in? The main reason I'm asking is because I want to get one of the Range AFM disablers, and I'd like to see, live, if it ever switches in to 4 cyl mode. Thanks in advance for any help you can provide