2025 GMC Yukon Powertrain & Transmission Problems

ENGINE died rattling sound undeer car shaking loss of power

While driving on a highway, the vehicle intermittently suffers a sudden loss of engine power during acceleration, accompanied by a flashing check engine light. The most serious event occurred while merging into traffic when the vehicle failed to accelerate normally and briefly lost power, creating a risk of being struck by faster-moving vehicles. Pulling over and restarting temporarily restores normal acceleration, but the problem recurs. The malfunction appears consistent with an engine misfire/powertrain fault. An OBD scan has shown misfire-related diagnostic codes (random/multiple misfire and a cylinder-specific misfire). The condition is intermittent and often occurs after approximately 10–45 minutes of driving. The vehicle remains available for inspection. The vehicle has been presented to authorized service departments multiple times. Dealers reported they were unable to duplicate the issue during road testing and no lasting repair has been completed. The manufacturer has been contacted and the vehicle has been evaluated through authorized service channels, but the underlying cause has not been identified. This remains a safety hazard because it reduces acceleration in traffic. Incident list: • 10/25/2025 (~12:25 PM; ~3,108 miles): Loss of power while merging; flashing CEL; restart temporarily resolved. • 10/27/2025–11/04/2025: Intermittent recurrence, usually lasting a few minutes then clearing. • 11/05/2025 (~8:01 AM; ~3,641 miles): Flashing CEL and misfire/loss-of-power symptoms; taken for service. • 11/26/2025 (~10:06 AM): Another episode consistent with the same pattern. • 12/17/2025 (~8:21 AM): Another episode, including during travel to a service visit. • Ongoing: Episodes after ~10–45 minutes; sometimes requires restart to restore drivability. Observed codes: P0300 and P0301. Safety risk: loss of power during acceleration/merging increases risk of rear-end or side-impact collision.

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.

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 would like to express my frustration and concern regarding a serious issue with our brand-new 2025 Yukon Denali truck. The vehicle, which has only 934 miles, has experienced a transmission failure. We picked the vehicle up on [XXX] and since February 27th, it has been at the dealership for repairs—now more than a full month. Initially, the torque converter was replaced, but that did not resolve the issue. After only a mile or two of driving, we returned the truck back to the dealer for further evaluation. Subsequently, after consulting with technical assistance, the dealership confirmed that the valve body needs replacement. As I'm sure you're well aware, this part is backordered nationwide, adding significant delays to an already troubling situation. It is hard to comprehend how a brand-new truck can fail virtually right off the assembly line. I am disappointed that we have had to deal with such a significant defect and even more disheartened by the extensive wait for repairs. This experience has left us questioning the safety and reliability of our vehicle. Given the circumstances, I believe more should be done to resolve this matter quickly and effectively for us. GM has been well aware of this transmission for years. The most recent recall dated December 13, 2024 for the same issue on the 2021 – 2022 model years of most of GM’s product line suggest this problem has not only been a known issue for many years but with the failure of my new vehicle for the same issue proves that they have not done anything about it. This leads me to believe that my safety is just as at risk as anybody else in the earlier named recall and therefore this recall should be extended to include all current models. GM should be forced to resolve this issue for existing vehicles before they build any new defective vehicles and sell them to unsuspecting customers like myself. Thank you for hearing me out, I look forward to your guidance. Jason FYI there is an interesting article o INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)