2025 GMC Yukon

My 2025 GMC Yukon AT4 Ultimate experienced reduced acceleration, and I immediately took it to the dealer. The dealer concluded it was a thrust bearing failure, and GM has authorized a complete engine replacement. I wanted to report this issue, as I believe it represents a potential safety concern. I would like to clarify whether GM has identified the root cause of this problem and redesigned the replacement engine to prevent recurrence. Additionally, I want to be able to track the replacement engine through its serial number for documentation purposes. I am submitting this report to formally document my concern. While GM has acknowledged the thrust bearing issue through a memo #25-NA-307, they have not confirmed whether the redesigned replacement engine will prevent this failure from happening again. Please advise. Sincerely, [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I bought a brand new 2025 GMC Yukon AT4 3.0 Diesel on 8/16/25 (had 213 miles on). A month later, with only 2000 miles on the vehicle, I was driving down the road and got a warning "reduced acceleration, drive with caution". Car would hardly accelerate. Had it towed to the dealer on 9/22/25. They found metal shavings in the engine oil. Said there was a quarter inch play around the camshaft (manufacture defect). Told me I need a completely new engine. It's now 12/2/25 and I still don't have a car, and mine hasn't been repaired.

On November 5, 2025, this 2025 diesel GMC Yukon Denali brand new vehicle went into "limp mode" 75 days after purchase with 3,957 miles on the odometer. Vehicle began to decelerate on a busy road. Warning lights went on to indicate that accelerating was no longer possible. Other fast-moving vehicles on the road came very near to the Yukon and quickly passed it/weaved around it, jeopardizing the lives of this Yukon's driver and occupants. At times, the Yukon diesel vehicle would only reach 15 MPH. Vehicle eventually driven to nearest GM dealership. The GM dealership service center reported a P06D code and reported that the engine experienced catastrophic engine failure. A new diesel engine has been ordered but is not yet available to the dealership for installation. (The dealership also reports that two other new GM diesel SUVs are waiting on new engines due to catastrophic engine failure.)

On October 21, 2025, with only 4,197 miles on my Yukon, the vehicle suddenly died while in drive in a parking lot. The vehicle would not restart or shift into neutral. I contacted OnStar, who arranged for the vehicle to be towed to the nearest GMC dealership. Since that date, the vehicle has remained at the dealership and has been diagnosed as needing a complete engine replacement due to metal shavings found in the engine. There were no warning lights, messages, or performance issues prior to the failure. This incident was both unsafe and alarming, as the vehicle shut down unexpectedly without any warning while I was driving. I would like to understand how such a major failure could occur on a brand-new vehicle with so few miles.

Driving through the intersection of N. Scottsdale Road and E. Bell Road in Scottsdale AZ my collision warning red light flashed on the screen and the engine turned off. This caused me to lose forward propulsion and forced me to navigate to the side of the road to avoid being hit by another car. At Van’s GMC, the service manager told me that we experienced a catastrophic engine failure and that the engine seized. Vehicle has been inspected, but I have not received an official diagnostic even though I have requested. There were no warnings or indications that the vehicle was compromised prior to the engine turning off.

My vehicle, with only 2,400 miles on the odometer, has been diagnosed as requiring a full engine replacement. While driving on the interstate, a warning message appeared indicating reduced acceleration. I was able to exit the freeway safely, but the vehicle could no longer maintain adequate speed to match traffic flow. Prior to this, the check engine light came on, but no issues were reported in the vehicle’s status system. I contacted OnStar, and they advised me to take the vehicle to a dealership within seven business days. It has since been at the dealership awaiting parts. Upon further research, I discovered that this issue appears to be widespread. General Motors has issued a technical bulletin addressing the problem, which involves complete engine replacement. Additionally, the audio system intermittently emits a loud crashing noise that is startling and potentially dangerous—it has caused me to veer off the road due to its intensity. This issue also seems to affect other 2025–2026 Yukon and Tahoe models.

While traveling on the interstate at 10:30p, 6 hours into a highway trip, the vehicle shuttered violently and lost propulsion and powered systems control. We were traveling at 75 mph on cruise control and immediately had to take evasive action to avoid other vehicles traveling at highway speed as our vehicle rapidly decelerated to a stop. We were barely able to get to the shoulder of the highway before the vehicle came to a complete stop and all dashboard lights illuminated. There was no warning or indication of immanent failure or engine issue. The catastrophic engine failure did not allow for the attempted restart. After opening the engine bay we noted that the coolant reservoir was empty but there was no indication of any leaking fluid in the engine bay or on the ground. The coolant levels were normal at the trip start. We were stranded on the side of the busy interstate for approximately 2 hours awaiting OnStar assistance and were forced to exit the vehicle due to its proximity to the edge of an active lane, leaving us exposed and without any protection for 2 hours, in the middle of the night, until assistance arrived. It was a harrowing experience and we are lucky that we were not injured or killed. The vehicle could not be disengaged from park and had to be dragged onto the flatbed. It was taken to the local GMC dealership and left for diagnosis. It was determined that the #2 piston rod broke, smashed valves and sent metal into all engine systems. Bothe the engine and coolant system were replaced. In addition, the torque converter locked up and had to be removed during servicing. All parts were retained by GM.

I just bought this 2025 GMC Yukon a little over a month ago, and the 6.2 engine has seized up. This vehicle started making grinding noises and shut down going 60 miles an hour. I traded in my previous Yukon and the dealer has sold it, so now I have nothing to drive. These engines are dangerous, and GM knows this and they don't seem to be doing anything about it