2023 GMC Sierra 1500

On 9-10-26 Engine spun rod bearings per the dealership repair order Miles 52,796 I was towing a car on a car trailer traveling down the interstate when the motor failed. I had my wife in the truck with me. No prior warnings just a check engine light right before engine failed. GMC dealer replaced engine and returned on 9-14-26. The truck had already had the recall to check the engine and replace the oil to a thicker oil.

A GM warranty engine replacement was performed at Heyward Allen GMC in [XXX] on XXX at 70,415 miles. We purchase the vehicle on XXX with 73,904 miles and after driving for a month started having multiple malfunction indicator lights displaying, and experienced a no start condition. We took the vehicle to the Don Ledford GMC dealer in [XXX], and they performed a high level inspection. They found missing mounting brackets, loose wiring harness wires, broken and missing bolts. Issues all related to an engine replacement procedure. Deeming the vehicle unsafe to operate. The origin dealer that was paid through GMC to replace the engine is now refusing any responsibility for resolving these issues. Technicians have video evidence of the workmanship issues, documenting the sub- par repair work performed during the engine change. The vehicle now sits at the Don Ledford GMC dealer awaiting an estimated $4400 repair, before the vehicle is safe to operate on the road. The vehicle has been at the Don ledford dealer since XXX, and is still there today, XXX. 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 while driving 65 MPH, the engine made a clunking, knocking, and tapping sound. The engine was driving on seven of the eight cylinders. The contact slowed down and pulled over. The engine warning light was illuminated. The vehicle was taken to the local dealer and was diagnosed with a detached valve. The vehicle was repaired under an extended warranty. The dealer informed the contact that the failure might recur. The failure mileage was approximately 12,998.

The 6.2 engine in my truck failed while driving and it has been determine that I need a new motor. This motor was on the recall list. I brought it in for the PICO recall test in October we 2025 and it passed. They then changed the oil for a much more expensive 0w40. The engine failed in August leaving me stranded on side of the highway. It has been at the dealership since August 7th. There is no eta on when the new motor and parts will be available because I’m being told that some parts are on back order. I have looked into trading it in and the value of this truck due to the 6.2 engine recall is significantly lower that it should be. It’s half of what I paid for it 3 years ago. I incurred towing fees and Uber fees. I am no without a truck to tow with.

I am reporting a serious safety concern involving a 2023 GMC Sierra 1500 Denali, 6.2L L87 V8, VIN [XXX]. This vehicle has now experienced two catastrophic powertrain failures at very low mileage. The first catastrophic engine failure occurred at approximately 23,696 miles. The vehicle was taken to a GMC dealer, where the repair documentation states that the engine had suffered significant internal damage, including damage to the #3 connecting rod, a missing connecting-rod bearing, bearing material throughout the engine, and a scored crankshaft. The dealer determined that the engine was seized and required replacement. GM replaced the engine under warranty with GM engine assembly part number 12740076. The vehicle has now experienced a second catastrophic failure. On [XXX], while traveling approximately 40 mph, experienced grinding, lurching, and knocking, followed by a complete loss of propulsion. The truck would no longer move and had to be towed to a GMC dealer. At the time of the incident, no warning lights or warning messages were observed. The transmission is also suspected to have failed, although the exact cause and extent of the transmission failure have not yet been determined by the dealer. I understand that NHTSA is currently investigating failures involving GM 6.2L L87 engines, including failures occurring after previous recall remedies and engine replacements. I am therefore requesting that this incident be included in NHTSA’s investigation and considered when evaluating the effectiveness of the existing recall remedy and the safety of replacement L87 engines. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I am reaching out to NHTSA due to a vehicle that I believe will get me and/or my family in a major accident and cause serious injury or death. The vehicle that I had purchased in 07/08/2025 had a clean history report and was bought at 54,587 miles. It started having issues 8,563 miles later (odometer reading 63,150 ) on a trip that was 400 miles round trip. I was driving the vehicle on a highway at 65 mph and i felt a knocking vibration in the pedal it was not long before i could even pull over when the engine throttle had completely lost power causing the vehicle to almost come to a complete stop immediately having to steer onto the shoulder. after failing with no check engine light or warning present during the use of the vehicle on the road. it was giving off high temp/engine overheating with the engine making a continuous knocking sound in the engine. It eventually seized to work completely not being able to shift into neutral to push, and had to get it towed to the dealership 204 miles away. GM had advised the dealership to replace the whole engine which they did, and that second engine had given out 678 miles later (odometer reading 63,828.) I am now on my THIRD engine and i cannot trust or rely this vehicle for saftey or transporation. i have reached out to GM to file a claim and attempt to adress this issue to try and come to a resolution, however they denied my claim and have said that i am not "eligible" for a buyback program. I am considering getting legal attorney this is very frustrating to say the least GM is a terrible manufacturer for this issue

While driving, my 2023 GMC Sierra with the L87 6.2L engine experienced a sudden, complete, catastrophic loss of engine power. There were no warning lights or messages prior to the failure. This was a one-time event, but it left the truck inoperable and I have been without the vehicle since it happened. The vehicle had recently passed applicable recall checks and had a routine oil change performed, so it was properly maintained leading up to the failure. A sudden loss of engine power while driving poses a serious safety risk, including the possibility of a collision if it happens in traffic or at highway speed. It is unknown whether a dealer has confirmed the root cause, as the vehicle has been out of service since the incident.

My wife and I were driving on the highway going slightly uphill. I pushed the pedal a bit because the power wasn't keeping speed. It continues to not maintain so pushed throttle further and the truck stalled. We traversed 3 lanes to get to the shoulder. When I stoped I tried to restart but the car wouldn't turn over but all electrical were working. We were on the shoulder for over and hour on a main highway. We had aaa tow it to the dealership where they confirmed the engine was seized and will be ordering parts. The car is still available upon request. Our safety was at risk from loosing power on the interstate and sitting on the shoulder is very dangerous. I didn't receive any warning lights prior to this occuring. The truck did undergo the peko test and passed and added new oil viscosity. It had roughly 55k miles on it. Always changed the oil before it hit 0% oil life as told by dealerships.

1 - The Engine or something electrical, possibly the ECM, failed or malfunctioned, and yes, it is available for inspection. 2 - The vehicle lost power, reduced speed, was hard to steer, and I couldn't put the hazard lights on; this occurred twice while driving on the highway, once I was driving at approx 75 mph. The results could have been catastrophic not only to myself but to others on the road. These two events are not the only times the truck did this. 3 - No. 4 - No. I filed a claim with GM, but it has been approximately a month, and I've received no updates. 5 - No. Further: This event has occurred 6 times. I've taken it to the dealership three. They cannot duplicate the issue, so no repairs have been done. Apparently, approximately 100 codes come up, but they cannot diagnose the problem.