NHTSA Complaint #11657665 — 2021 GMC YUKON

I have had major transmission failure in my 2021 GMC Yukon Denali (6.2L V8, 10-speed automatic). The vehicle has approximately 72,000 miles. Recently, a critical internal clip/retainer in the transmission broke loose, sending metal debris throughout the transmission. This catastrophic failure has rendered the vehicle undrivable and requires a complete transmission replacement. Unfortunately, the vehicle is just outside the powertrain warranty, yet I firmly believe this failure is due to a manufacturing/design defect – not normal wear and tear. I purchased this Yukon Denali as a premium, flagship SUV and have maintained it carefully. I expected the transmission to last well beyond 72k miles under normal use. It is disappointing and that a core component failed so early. Not only has this imposed a significant financial burden, but it also undermines my confidence in the vehicle’s safety and reliability for my family. A modern transmission should not self-destruct at this mileage, especially given GM’s reputation and the Denali’s top-of-the-line status. Importantly, I have discovered multiple known issues and GM bulletins related to the 10-speed automatic transmission used in my Yukon. For example, GM issued a major recall in late 2024 (NHTSA Campaign 24V797000, GM recall #N242454440) affecting 2021 Yukon models (among others) due to a defective transmission control valve that could fail and cause the rear wheels to lock up, this demonstrates that GM has acknowledged serious problems in the 10L80/MQC 10-speed transmission design. Additionally, a recent GM service bulletin (PIP6008C, Jan 24 2025) indicates that internal transmission retaining rings can dislodge, causing the internal gears to separate – which leads to loss of reverse and internal damage. This scenario is similar to what happened in my transmission. My family was left stranded away from home with no warning. The vehicle just stopped working. The warning lamp did not come on until diagnostics was run.