2023 GMC Sierra 1500

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle shuddered while in first gear. The contact stated that the transmission sounded strained and shifted rough before slamming into gear. The vehicle was taken to the dealer; however, no cause for the failure was found. The dealer diagnosed the vehicle and determined that the vehicle was oversteering while turning to the right. The dealer replaced the valve and torque converter. On another occasion, while driving at an undisclosed speed, the vehicle accelerated independently. Most recently, a burned transmission fluid odor was coming from the front of the vehicle and entered the cabin through the A/C vents. There oil stains found on the ground on several occasions. The vehicle was taken back to the dealer and the valve body was replaced, the fluid levels were checked, and the transmission filter was replaced; however, the failure persisted. The contact called the dealer, and the dealer towed the vehicle. The dealer determined that the oil cap was loose. The vehicle remained at the dealer unrepaired. The manufacturer was made aware of the failure, and a case was opened. The failure mileage was 8,496.

Vehicle: 2023 GMC [MODEL], Black Widow package, 6.2L L87, 41,078 miles Recall: 25V‑274 / GM [XXX] ; recall remedy performed by Marty’s GMC (Kingston, MA) on 2025 -11-12; oil changed per recall procedure Post‑remedy symptom: intermittent knock starting ~01 - 2025 / about two months after remedy Incident: Jan 23, 2026 — engine seized / loss of propulsion while driving; stranded on highway off‑ramp; vehicle impeding traffic causing dangerous conditions. Codes: OBD scan by passerby indicated camshaft position sensor / correlation error (exact code not captured) Crash/Injuries: none Current status: vehicle at Marty’s GMC since Jan 23; not diagnosed as of Jan 29; GMC case #88159466 Safety concern: sudden loss of motor power in traffic after recall remedy On Friday, Jan 23, 2026, while my daughter was driving, the engine seized / the vehicle lost propulsion and stranded her on a highway off‑ramp. The vehicle was impeding traffic and had to be moved. It restarted briefly and was moved to a safer location but still impeding traffic. A motorist scanned the OBD port and reported a camshaft position sensor / cam-crank correlation error (exact DTC unknown). No crash occurred and no injuries occurred. The vehicle has been at Marty’s GMC since Jan 23, 2026 and as of Jan 29, 2026 it has not yet been diagnosed. I opened a case with GMC Customer Assistance (case #XXX). This is a safety-related loss-of-propulsion event occurring after the recall remedy was completed. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2023 GMC Sierra 1500. The contact stated that when the vehicle was started and shifted into drive(D), the accelerator pedal was depressed, and the vehicle responded slowly. While driving at an undisclosed speed, the vehicle decelerated and stopped unintendedly. The "Parking Brake” warning light illuminated. The contact stated that once the vehicle had warmed up, the unintended stopping ceased. The contact stated that the failure was intermittent at first but had become a recurring failure. The vehicle was taken to a local dealer where it was diagnosed and determined that the valve body needed to be replaced; however, the part to complete the repair was on a national back order. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 60,000.

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving uphill, the vehicle unexpectedly lost motive power. There was no warning light illuminated. The vehicle failed to restart and was towed to the dealer, where it was diagnosed, and determined that the engine block had failed and needed to be replaced. The vehicle was repaired. The contact stated that later, while driving at an undisclosed speed, the vehicle failed to shift into gear properly and jerked abnormally. There was no warning light illuminated. The vehicle was returned to the dealer and was diagnosed with transmission failure, requiring the PCM/TCM to be reprogrammed. The vehicle was repaired. The contact stated that while driving at an undisclosed speed, the check engine warning light illuminated, and the vehicle was taken back to the dealer, where it was diagnosed and determined that the fuel injector and coolant pump had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure, and a case was opened. The approximate failure mileage was 57,000.

I am writing to formally file a safety complaint regarding the ongoing recall of the GMC/Chevrolet 6.2-liter V8 engine and what I believe to be an inadequate and insufficient remedy being provided to vehicle owners. I purchased a brand-new 2023 GMC Sierra AT4 equipped with the 6.2-liter engine. I drive approximately 6,000 miles per year and maintain the vehicle carefully. After receiving the recall notice, I promptly took my truck to an authorized GMC dealership for inspection and repair. The only action taken was an oil change to a heavier-weight oil. I was told that everything was “fine” and that no further action was required. I find this remedy unacceptable given the severity and nature of the reported failures associated with this engine platform. Simply changing to a heavier oil does not address the underlying mechanical risks and does not provide owners with meaningful assurance that catastrophic engine failure will not occur without warning. This issue is particularly serious for me because I rely on my vehicle for my livelihood. I am an account sales executive and use this truck extensively for work travel and customer meetings. If my vehicle were to fail unexpectedly, it could cause me to miss critical business meetings, resulting in immediate financial loss and potentially long-term damage to customer relationships and sales performance. The current remedy provides no confidence that such a scenario will not occur. In addition, this recall has materially harmed the resale and trade-in value of my vehicle. Dealerships are now significantly lowballing trade-in offers because the 6.2-liter engine recall is widely known and prospective buyers are reluctant to purchase these vehicles. Buyers are also aware that any future owner will not receive the benefit of the original powertrain warranty coverage in the same way, further depressing resale value. As a result, I am effectively trapped in a nearly new vehicle that has become difficult to sell or trade due

This malfunction is ongoing and the dealership cannot fix the problem. The first time it happened in September 2025. I was driving down the road and the gauges started to go crazy. The screen on the dash said reduced acceleration. Then it said Service ESC. Then it said Service Traction Control. It would not let me go over 40 mph. I took it to the dealership and they told me I needed a valve body replacement. They installed the valve body and that did not fix the problem. It happened again and said reduced acceleration took over forcing me to pull over on the side of the road. The GMC dealership said to bring it in again but they could not reproduce the malfunction after driving for a week. It happens randomly. The third time this happened I was traveling up interstate 24 at about 70 mph. There were semi trucks around me when the malfunction happened and my acceleration and speed was reduced throwing the RPMs as high as they would go, and I was almost hit by a semi trying to move out of the way and onto the shoulder of the interstate I tried to accelerate to get out of the way of the semi truck but could not. I had to swerve over almost losing control of my truck. I informed the dealership that this had happened again and they asked me to bring it in. I did. They told me they were going to clean corrosion off of ground wires, and that should fix the problem. It did not. This keeps happening and I feel that the vehicle is not safe to drive. I do not know when it will happen again. I travel for a living and I feel the vehicle is unsafe to operate.

I had the truck inspected for recall N25249400 on August 11, 2025 with 24,610 miles. It passed the recall inspection and the dealer changed the oil to GM recall recommended oil. On January 18, 2026 with 28,275 miles, the engine seized while on a major highway. The truck lost all power and just turned off amd would not start or turn over. The vehicle was towed by the Police due to the vehicle being in a dangerous spot in the middle of a lane on the highway whi h I had to pay out of pocket. January 19, 2026, the GM dealer confirmed that the truck needs a new engine due to the recall defect. They said that they had just ordered a new engine, but does olnot know hpw long ot will take to get and then install. The dealer is unable to provide a rental vehicle which means, I can't WORK!

Vehicle passed initial inspection and had higher viscosity oil installed. After driving for the past six months I noticed a burning oil smell inside the truck. The smell gets intense at times especially during highway driving. The OW-40 viscosity oil is causing high fumes within the cockpit. Please consider checking this issue out during your added investigation into the L-87 engine failure. I shouldn't have to drive with the windows down but I do. I will have the truck inspected during my next oil change next week.