AFM lifters failed which caused cam shaft to collapse under 35k miles. Had to remove while front end to repair

- Plantation, FL, USA

Subject: Complaint Regarding Recurring Engine Failure in 2021 GMC Sierra AT4 Dear National Highway Traffic Safety Administration, I am writing to formally express my concern regarding recurring engine failures in my 2021 GMC Sierra AT4 (6.2L engine). At 23,000 miles, the vehicle suffered a complete breakdown due to failure of cylinder #8, lifters, and push rods. General Motors covered the repairs at that time. However, at 97,000 miles, the exact same issue reoccurred, resulting in significant engine damage. The dealership diagnosed a misfire in cylinder #8, leading to the removal of the right cylinder head, where they found a bent push rod, spun lifter, damaged camshaft lobe, and lifter roller. The repair estimate totals $9,746, but GM has refused to cover the costs, despite us having an extended warranty purchased from the dealership. This recurring failure raises serious concerns about engine reliability and manufacturing defects in General Motors vehicles. I urge the NHTSA to investigate this issue, as multiple GMC and Chevrolet owners have reported similar problems with the 6.2L engine lifter and camshaft system. This is not just a costly repair but a potential safety hazard that GM has failed to properly address. Thank you for your attention to this matter. I appreciate any guidance or action the NHTSA can take to hold GM accountable and ensure consumer protection.

- Pharr (, TX, USA

My Vehicle went into the dealer on January 21, 2025. My initial complaint was tapping noise, I was advised that my vehicle had collapse lifters issue several days later I was informed that they have found metal shards in the lower end and found a bad crank bearing and crank. I was told that the vehicle will need an engine replacement, and that the engine is on back order with no date of fulfilment. My vehicle has 66,700 miles I was advised was out of warranty and that GM will only cover half of the estimated cost of $11,000.

- Voorhees, NJ, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at approximately 80 MPH, the vehicle stalled and failed to return to normal operation. No warning light was illuminated. The vehicle was towed to be diagnosed. The contact was informed that the rod bearings needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 134,000.

- Springfield, LA, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 55 MPH, the vehicle started making a knocking sound. There were no warning lights illuminated. The contact picked up his son from school and drove the vehicle to the dealer. The contact stated that while depressing the accelerator pedal, the knocking sound became louder, and the vehicle was losing motive power. The vehicle was taken to a dealer and diagnosed with engine failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 58,522.

- Pequot Lakes, MN, USA

While driving on the highway the engine 6.2 GM seized suddenly at high speed. The truck shut off completely and left rolling without any control. I had work my way accross lanes to the breakdown lane. While doing so I was almost hit by an 18 wheel trailer truck, who luckily was able to change lanes to avoid hitting me. The reason I was almost hit was because of my low speed since I had now power or acceleration.

- Bridgewater, MA, USA

I purchased a new 2021 GMC Sierra Denali with a 6.2L engine on 03/05/2022. On November 10, 2022, I started the truck, and the engine seized up. The truck had 9018 miles on it and 274 engine hours. The main bearings and possibly the connecting rods bearings was the problem. On January 27, 2023, I finally got a new engine installed in my truck. I had to pay for the repairs.

- Larwill, IN, USA

Driver side lifters collapsed and push rods failed on freeway without warning at 12900 miles on truck.

- Imperial Beach, CA, USA

On the morning of 1/19/25, my 2021 GMC Sierra 6.2L AT4 went into limp mode heading south on HWY 207 in Leavenworth, WA at approximately 60 m.p.h. Fortunately, I was able to avoid a rear end collision. I quickly turned the truck off in the middle of the road and restarted it with a CEL. When I returned home almost 180 miles away, my local mechanic diagnosed a code P0303 and cleared it. Since, the truck has continued to shutter at various speeds without throwing a code. It is currently at Haselwood GMC in Bremerton, WA being scanned, recorded, and findings set to GM waiting for resolve. I have notes, exact dates, times, call records, return voice mail messages, and dealership personnel spoken to, etc. The dealer-??s lead technician and I were able to replicate the shutter on a road test together on 1/27/25 at 3 p.m. after having driven just 10 miles. During my visit on the morning of 1/30/25, the lead technician stated he has since been able to replicate the shutter seemingly getting worse. I was strongly encouraged by the service manager, service writer, and lead technician their collective -??personal recommendation-?? was to not take the truck back. Haselwood has had the truck since 1/27/25. Still awaiting a response and resolution.

- Seabeck, WA, USA

lifters in the left and right side snapped into 3 pieces. Caused engine failure happened 2 different times. All before 50,000 miles. The first time was before 30,000 miles.

- Alabaster, AL, USA

Engine failure

- Little Silver, NJ, USA

We have had several times where we are on highway and our truck like slams on the brakes causing us to lose control. It was a recall on it and GMC fixed it and within the same week of them fixing it it happened 3 times back to back. Making my truck to force another car to steer out of my way and actually went off the highway. Thank god it was just dirt snd he didn-??t get hurt or anything. But I am scared to even drive my vehicle! It starting Happening for about a year now. And it would only do it like every couple months but now it-??s has done it 6 times in the last 2 months!

- Tehachapi, CA, USA

I was notified at the dealership that my truck had metal in the oil that is causing the oil sensor pump to send a ln engine code. The fix is a new engine.

- Fenton, MI, USA

Engine knocking and metal in oil. Been to the dealership and even though it's under warranty they will not act on it due to no check engine light present. It's making it difficult to trust driving the vehicle anymore because of the thought of the engine shutting down without warning anytime. This complaint is documented and confirmed by a dealership. They made me pay the check out fee and recommended i keep driving the vehicle until the motor locks up.

- Redway, CA, USA

Le Moteur Le 13 décembre 2024 le véhicule arrêté subitement je tente de le redémarrer et ne demarre plus à plusieurs reprises je branche un obd2 et cela indique crank sensor j'envoie le véhicule au dealer et me dise qu'il y a quelque chose dans la base et aujourd'hui ils y est encore Les pneus Certains Flan de pneu de ce véhicule sont fissures tous le tour des roues

- Princeville, VT, USA

Lifter noises, error codes for misfires, lost power

- Rock Hill, SC, USA

I got off work started my truck heard a few pops. As I was driving the vehicle started jerking like the brakes were being applied. Then I noticed a yellow engine light and a ESC light come on. I pulled over to check vehicle and all the lights went off. Dealer was just a few miles away. So I started back up and drove to dealer. On the way to dealer vehicle started a tapping noise. Then a new message flashed something about my steering will be affected. I got I to dealer safely. Where I left the truck for repairs.

- Greenwood , IN, USA

We had to replace the transmission at 70,000 miles even though problems were reported to the dealer at 53,340. This repair costed $2300 on a 1 year old truck. Then we needed to replace a solenoid circuit which was not covered under warranty. We repaired this 2x (the second time covered). Then at 147,000 miles 9/24, there was a cylinder misfire which bent the push rod and collapsed lifter. This engine repair cost $8300 dollars. Who has to replace an engine on a truck that's 3 years old. This is a defect. Please help us. We have spent over $10,000 on repairs. We faithfully do our changes and service.

- Sanbornton, NH, USA

Multiple injector and lifter failures. Occurred on 2 separate occasions. Taken to dealer the first time. Told injector failure and lifter failure. Less than a week later experienced multiple lifter failures. Taken to dealer again for repair. They only replaced some of the affected lifters, even though TSB from GM recommends replacement of all of them. Currently awaiting failure of additional components not replaced. There was no warning of either occurrence. Was only driving 45 mph on my way home the first time. The second occasion was on initial start up at Dr office. Opened a claim with GM on my own, as dealership was negligent or unwilling to contact GMC about these failures, even though I provided them with the appropriate TSB directly from GM.

- Lacenter, WA, USA

Engine failed due to a loss of oil pressure. Rod bearing failed which cause metal to be dispersed throughout the engine causing the engine to seize from a sudden loss of oil pressure from oil pump failure. Engine was replaced in June 2024 failure happened in May 2024. While driving a system message came on DIC that stated pull over immediately to prevent engine damage and no oil pressure. I was driving uphill with cars on my right in the #2 lane. Engine shut off before I could pull over resulting in decreased braking power and a lack of steering. I almost hit 2 vehicles trying to pull over to get my family to safety on the right hand shoulder. I couldn-??t pull over to the left hand shoulder as there was a guardrail in the way. When I got my vehicle pulled over the only thing that stopped my vehicle from going over the cliff was a bunch of wood chips on the right hand shoulder. From the time the warning lights came on to the time the engine shut off and seized was maybe 5 seconds. It took 31 days to replace the engine and the dealership did an inspection on the engine. There was absolutely no warning there was any problems until the lights came on. My wife and [XXX] and [XXX] were in the vehicle at the time this happened. It was so dangerous where we broke down California Highway Patrol stayed behind my vehicle with its lights on. It was also a fire hazard with the exhaust sitting on the dry bark. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- Orland, CA, USA