The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling). The contact stated that while driving at approximately 50 MPH, there was a loud squeaking sound coming from the front driver-??s side of the vehicle before the vehicle lost power. Simultaneously, the check engine warning light started blinking. The vehicle was pulled over to the side of the road and the sound became louder, before becoming a knocking sound. The vehicle was restarted, and the failure persisted. The vehicle was towed to the residence. The vehicle was not diagnosed or repaired, but a dealer stated that there was as recall associated with the VIN; however, parts were not yet available to repair the vehicle. The manufacturer was not notified of the failure. The failure mileage was approximately 128,000. VIN tool confirms parts not available.

- Christiansted, VI, USA

Was informed from by GM that my vehicle is involved with a recall an still hasn't been repaired

- Statesville, NC, USA

What component or system failed or malfunctioned, and is it available for inspection upon request" The valvetrain system failed due to broken rocker arms, which resulted in additional internal engine damage. This failure occurred under normal driving conditions. The affected components have not yet been discarded and are available for inspection upon request.How was your safety or the safety of others put at risk? The failure caused sudden engine misfiring and knocking, reducing engine power while I was operating the vehicle. This significantly compromised acceleration and response time, especially during merging and lane changes, which could have led to an accident. Any unexpected loss of power or engine instability at highway speeds poses a serious risk to myself, passengers, and other motorists.Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. The issue has been diagnosed and confirmed by an independent certified mechanic, who verified the broken rocker arms and resulting engine damage during inspection.Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? The vehicle has not yet been inspected by the manufacturer, police, or insurance representatives. Only a certified independent mechanic has inspected the failure thus far.Were there any warning lamps, messages, or other symptoms of the problem prior to the failure, and when did they first appear" Yes. The check engine light appeared and the engine began running rough and producing a knocking sound. These symptoms occurred just prior to the confirmed failure and prompted me to stop driving the vehicle immediately and have it inspected. Given the seriousness of this issue and reports from other GMC 5.3L engine owners experiencing similar rocker arm failures, I urge the NHTSA to investigate this potential defect. It poses a real and significant safety risk.

- Buford, GA, USA

On Dec 27 I noticed a skip in my engine when I started the truck. I took the truck to Cronic Buick GMC on Jan 6 for an inspection. They reported to me that the engine failed.Seized up. I reported the incident to my extended warranty company Warranty Solutions. They refused to do the repair because I was late for an oil change in 2022. After 3 weeks and no cooperation I contacted GM customer service. I was assigned an agent that help initiate the engine repair. The repair was completed on April 12 (3 months after the failure). I paid $4600 out of pocket for a portion of the engine repair.

- Lagrange, GA, USA

Replacement part needed is COOLANT CONTROL VALVE according to diagnostics at local GM dealer service department after noting check engine light was on. YES, it is available for inspection. Told unsafe to drive as it would very likely overheat or worse. It has been in the shop for a month (as of June 11, 2025) awaiting a backordered part, which we-??re told is a national backorder. No loaner vehicle available and told by service department that they have had another truck in for same problem for several months and that this problem is very common. PLEASE HELP us with getting the part needed!

- Ruston, LA, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated that upon starting the vehicle, there was an abnormal knocking sound coming from the engine. The abnormal sound ceased once the vehicle had accelerated; however, the abnormal sound returned while the vehicle was idling. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed that the ball bearing caused a misfire, and two cam lifters needed to be replaced. The vehicle was repaired. The contact picked up the vehicle and on the way home, the engine failed. The contact took the vehicle back to the dealer. The technician test drove the vehicle with the contact as a passenger, and the check engine warning light illuminated. In addition, there was an abnormal sound coming from the engine. The vehicle failed to accelerate as intended while depressing the accelerator pedal. The contact was informed that the engine failed and needed to be replaced along with the fuel body system. The contact was informed that as per GMC, the oil needed to be changed to an oil with a thicker viscosity. The fuel body was replaced, and the oil was changed. The manufacturer was made aware of the failure and offered the contact an amended warranty. The contact was informed that GMC had elected to participate in the procedures under the Song Beverly Act. The failure mileage was approximately 50,000.

- Paso Robles, CA, USA

The coolant control valve on my truck is causing issues. From doing research, this is an ongoing issue with the 3.0 duramax. The part is on nationwide backorder and I cannot drive my vehicle in reduced engine power because the only way I can get to work is by taking the interstate. It is madness that GM has not issued a recall or done anything to rectify this issue. Many GMC owners are paying on vehicles that they are unable to drive which is assanine. This part needs to be readily available due to the NUMEROUS complaints that have already been submitted in regards to this part.

- Pendergrass, GA, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated that upon starting the vehicle, the vehicle was idling abnormally, prompting the contact to turn off the vehicle. The contact stated that the check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the lifter in cylinder #4. The contact stated that the lifter had collapsed into the engine, causing damages to the engine and camshaft. The vehicle was repaired. The manufacturer was not notified of the failure. The failure mileage was 98,000.

- Caledonia, MI, USA

It started with a emergency brake light coming on, shortly (2 miles) later it started misfiring on cylinder #1 after replacing coil pack plug wire and plug. It then started smoking bad out of the exhaust. I knew GM was having recalls on the 6.2 engines so I hauled it to the dealer. They told me it was a bad engine and since it had aprox.62,000 miles on it and no recall it wasn't covered. Since then the dealer called the factory service rep. and he agreed to replace the engine at a 50% reduction in the price, but had no idea when they could get me a replacement engine. After a few days of research on my part I called the dealer again to get a price on how much it was going to cost me? The owner of the dealership ask me to give him a few more days to ask the rep. if he would agree to 100%. My problem now is I don't have it to drive, I can't sell it. and no idea how long it will be before it can be repaired. Plus I am still making payments on it. It is available for inspection at the dealer. If I had of continued to drive, it could have locked up causing a catastrophic accident. In my research it looks like these problems started in 2019 not late 2020 when mine was built. NC has lemon law complaints going back to 2019 that have been paid out. I currently own a #1 2007 GMC Yukon Denali 6.2 with aprox.389,000 miles and only replaced the transmission recently. #2 A 2008 GMC Sierra Denali 6.2 with 279,052 miles, new transmission. #3 A 2011 GMC Yukon Denali 6.2 with 234,361 miles and #4 a 2017 Cadillac Escalade 6.2 with aprox. 102,000 miles. All of these are working and driving on a daily bases. I have a lot of faith in these 6.2 engines until now, I will no longer be buying any more of these engines even though 1 out of 5 aint bad. Thank you for your consideration and for what you do. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- Surf City, NC, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated that occasionally while attempting to start the vehicle, the engine hesitated to turn over. The contact stated that the failure progressed, and the vehicle no longer started as needed. The check engine warning light was illuminated. The contact stated that two local dealers were contacted; however, the contact was advised that to diagnose or repair the vehicle, might take several months. The vehicle was towed to a local independent mechanic, where it was diagnosed with camshaft sensor failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 83,000.

- Carlsbad, NM, USA

Safety recall, unsafe

- Spencer, IA, USA

Engine experiences missing when accelerating in lower speeds...also now, and since driving for a few thousand miles, f umes are entering cabin frequently and causing nausea, 'headaches and burning of mouth, lips and eyes.....all the time. My youngest granddaughter got sick and so did my oldest son just this past weekend! As far as I know, police or dealership never inspected, nor did they acknowledge it! No warning lamps appeared

- Stephens City, VA, USA

I heard a ticking in the engine and noticed multiple warning lights in the dashboard. I called the GMC dealer and was told the next opening was several weeks away. I was also told that it would be OK to drive the vehicle which I did (~10 miles) and parked the truck in my driveway until I could get the truck in for a diagnostic evaluation. The service department at the GMC dealer where the vehicle was purchased identified a defective camshaft/lifter as the source of the noise and lights. The service manager recommended either an engine rebuild at their shop or purchase a replacement motor from the GMC inventory network. The serial # of the old motor is: 126852545. The serial # of the new motor is: 40208378. The cost of the new motor, replacement of required fluids and parts and labor was $12,360. 100% of the repair was paid by myself. The.pdf of the service record (RO #: 9189240) exceeds the 10 MB limit and cannot be uploaded. I have a hard copy if needed. The dealership where the vehicle was purchased and serviced is: TULLEY Buick - GMC - BMW - Mazda P.O. Box T 147 Daniel Webster Highway South Nashua, New Hampshire 03060 (603) 888-0550 www.tulley.com

- Bedford, NH, USA

I had an engine warning warning light on my dash around May 5th. A notice of reduced speed also lit up my dash while I was on the freeway. I scheduled a service for May 15th and was told the engine coolant flow control valve needed to be replaced. I was also told there was a backlog of other vehicles waiting for the same part. It has been over a month and I am still unable to drive my truck which I use for work.

- Vaughn, WA, USA

My Truck has been consuming oil since new, latest documented consumption test was 1.25 quarts in 1967 miles. GM dealership said that is normal and no further diagnosis is required. GM says acceptable consumption is 1 quart per 2,000 miles. This truck has a 6.2L engine that is not under the current recall ( N252494000 ). The engine problems affect more vehicles that the current recall and should be investigated.

- San Marcos, CA, USA

Dealer keeps ignoring engine knock noise states its normal, mpg is down dramatically. Shift to park, vehicle only has 34k miles and dealer does not want to repair under warranty due to vehicle being a 2021 Battery keeps draining for no reason, new battery added still does the same thing

- San Jose , CA, USA

Engine seized while at idle speed and has to be replaced. It was a catastrophic event, but not covered under the current recall for 6.2L L87 engines.

- Spring, TX, USA

While traveling on the interstate the vehicle lost all propulsion and started to rapidly decelerate. Shortly after propulsion was lost the engine turned off completely affecting the steering and braking of the vehicle. The vehicle was towed to the GMC dealership that we purchased it from. repairs have not begun so I assume it would be available for inspection. We were traveling on a three lane interstate up a grade at 80 MPH. Had I not been able to safely get the vehicle stopped and out of traffic or had we lost control going down a grade we would not have been able to stop the vehicle and there would've potentially been a catastrophic accident most likely resulting in injury or death. No the dealership has not diagnosed the failure physically. The service writer did suggest that it sounds like the failure reported from the recall not being addressed. I did contact the dealer about the recall on Saturday May6th. At which time I was informed there was not a solution for the vehicle for my vehicle at that time. There were no warning prior to the incident. After the engine stopped operating there was a warning produced on the instrument panel that read "Engine Oil Hot" and the instrument panel no longer registered any oil pressure.

- Hurricane, UT, USA

My truck has a known recall from GMC which results in total loss of propulsion. It has not failed yet, but this is dangerous to me, my family/kids, and potentially others on the road. I have made multiple attempts to speak with GMC about the issue and also my local dealer. Neither group will provide concrete information as to when they can look at/service my truck even though there is a known remedy - [XXX] I brought my car into the dealer December of 2024 for brakes and also a rattling noise since it was uncharacteristic. Noises can be indicative of this larger problem (which I know now and didn't then) but they "didn't hear a rattle" and the "condition could not be duplicated" which is patently false since it still makes the noise/has gotten worse. Since then, I have taken the following actions: - I called and spoke with the local dealer service team on 5/5 - was told since it's showing incomplete, no remedy available there was nothing they could do - Spoke with GMC on 5/5 - they directed me to the local dealership - Made an appointment online on 5/10 to get my truck serviced and to check for this problem - They immediately called me first thing on Monday 5/12 to cancel my appointment and again tell me there is nothing they can do about this issue - I have continued to express my safety concerns to both parties - I spoke to GMC today, 5/30 and was told that there is no timeline for the issue (with my VIN) even though the remedy is known - An appointment is scheduled on 6/12 with my local dealership, but if I recall status hasn't changed, they will not check for this problem INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- Duxbury, MA, USA

The truck ever since of bought it has been nothing but issues. Starting with the fuel pump issues then electrical issues and most recently the coolant flow control valve. This is my work truck and now I-??m out of a truck with no loaner and the dealership has no eta.

- Delavan, WI, USA