2023 GMC Sierra power train problems

“On XXX, at approximately 2:30am, about 30 hours after purchase, a 2023 GMC Sierra Denali Ultimate suffered catastrophic engine failure in [XXX] during a planned 20 hour trip. The vehicle had about 49,007 miles at purchase and 49,411 miles at the time of failure. The check engine light appeared during the trip. Over five hours into the journey, shortly after passing through a one-lane construction zone with no shoulder, the truck made noises, then lost driving power and began slowing among highway traffic. The dashboard displayed "LOW OIL PRESSURE STOP ENGINE," code P0016, and a transmission warning. I had to move into another lane to reach the shoulder. The sudden loss of propulsion at 2:30am created a serious crash risk because the truck could have been struck by nearby traffic or become disabled on the one-lane road without a shoulder. The engine had received the GM L87 recall remedy on XXX involving a change to 0W-40 oil. Despite this remedy, the engine failed while the vehicle was moving. The repair order lists replacements for the engine, radiator, oil cooler lines, intake manifold and gaskets, spark plugs and wires, water pump gaskets, high pressure fuel…”

“Purchased above listed vehicle new in XXX. Immediately noticed a 'coolant' smell in cab. brought vehicle in for coolant smell issue on XXX and XXX. We were told that there was no issue until finally on XXX we were told the radiator needed to be replaced at OUR expense. XXX we received a letter from GMC advising the "engine coolant control valve" may fail. In XXX while driving on mountain roads (we live in [XXX]) the check engine light came on and while at 50 mph, the vehicle went into "limp mode" we lost power and speed was immediately reduced. We now know that a symptom of that valve failure is coolant smell in the cab of the car, a problem we had attempted to address with GMC from the beginning. We could have had a serious accident driving on a busy mountain road when this failure occurred.”

“Truck rear wheels locked up while going between 45 - 50 mph nearly causing accident. Driver behind me had to lock-up their breaks to avoid collision. This is happening every time I drive the truck for more than 30 minutes. It is happening multiple times a day now. I cannot drive truck - too unsafe to drive. Tried getting serviced, but local GMC dealer said they are backed up with truck transmission issues and can't get mine in until Sep 15 - 3 weeks after first reporting. No warning signs. The locking of rear wheels takes me by surprise.”

“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…”

“While driving truck jolts (rear wheels lock up) then downshifts into a lower gear. Appears to be similar issue as described in Recall 24V797 and 25V148. Not sure why my VIN does not show up on recall. Based on description it is the same problem. Feels unsafe to drive.”

“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…”