NHTSA Complaint #11648325 — 2023 GMC SIERRA 2500

2023 GMC Sierra 2500 AT4 with approximately 36,000 miles as of current. The vehicle has experienced three valve body failures to date. GMC dealerships have completed one GM remanufactured transmission replacement and an overhaul of the second transmission. The third valve body has now failed. A GMC transmission specialist confirmed transmission failure upon recent test drive on 2/24/2025. GMC dealership refuses to perform warranty repair as they are stating “a recall is being developed” therefore will not repair/replace current defective powertrain parts. I was given the vehicle back with the verbal disclaimer “it should be safe to drive but the rear wheels can lock up at highway speed so be aware.” The failure causes extreme harsh downshifting and what feels like a momentary rear wheel lock up. I have experienced this numerous times at lower speeds (<40mph). The check engine light does not come on.