2025 GMC SIERRA 1500 Engine Problems

was driving truck and reduced acceleration drive with care comes up on dash pull over shut truck off start truck warning gone in 30sec back on and repeat drive off again then truck shut off while driving and try to start again and the dash went black motor did not turn over then tried again and same thing called tow company and had towed to dealership. dealership said it had 2 pages of codes and now needs a new motor........ no estimated time on getting my truck back

2025 GMC Sierra 1500 has had 2 engine failures since purchase date June 2025. Engine failed on a road trip with my family, leaving me stranded for hours. After the problem being resolved, engine failed once again after 5 months. On the dash it said loss of power and wouldn’t crank to turn ON

I was driving and the engine abruptly stalled. The truck self-shifted to Neutral. Once stopped, I shifted to Park to attempt a restart. It would not crank. I was on a 2-lane road so I did not have a shoulder. Once I realized it would not restart I tried to shift to Neutral so I could push it to a subdivision road about 50 yards away only to find out my transmission has no ability to shift to Neutral (the dealer confirmed this later). So I was stuck on the road for hours just over the crest of a hill with people coming up on me and my family at 50mph. It was a windy 10 degrees so we could not wait on the side of the road where we would have been safer. This is how people get killed; being stopped where people can't see you and do not...

I have the 6.2 L87 with the 10 speed transmission in my 2025 Sierra. At cold start, when auto stop restarts the truck, when the truck downshifts under 20 mph down to 12 mph the engine or transmission makes a chirping/squeak/squeal sounds. Several repair attempts have been made, parts replaced. According to GM and their “field engineer” this is a “normal characteristic of the dfm system”. They claim that it has to do with ignition timing. Not my first dfm truck, but it is the first to make this noise. There is not very many components in “the dfm system” that can make a metal on metal squeak/chirp/squeal sound other than lifters/pushrods, but the noise could be coming from the transmission/bell housing area. I am fairly certain this is an early warning sign of engine or transmission failure. Truck currently has 7,800 miles. If this was an actual “normal behavior”...

I bought my truck new in June 2025. On the night of December 29, 2025, with around 9,300 miles on the odometer, I began to hear a knocking sound coming from the engine while I was driving it back to my house from my mother's house. The sound got progressively louder and louder. The truck eventually displayed a "reduced acceleration drive with care" warning. I thought catastrophic engine failure was imminent and did not believe I could make it home. I called my in-laws (they were closer to my location than my house), agreed to park it there overnight, and thankfully made it to their house. The next day the truck was towed to the GMC dealership. A week later, GMC diagnosed this issue as a thrust bearing/crankshaft issue and agreed to replace the entire engine. A crankshaft issue in a new diesel engine should not occur, yet it did....

Driving at highway speed engine lost most power (limp mode), was able to get to an exit at low speed with flashers on but was creating a hazard on busy interstate. Dealer diagnosed truck needs new 3.0 liter duramax engine per GM TSB 25-NA-307, bad thrust bearing.

With approximately 5,200 miles on my new vehicle, received an error message on the dash while driving on 1/8/2026 that read “Reduced acceleration; Drive with care”. I immediately took the vehicle to a local GM dealership and was informed on 1/9/2026 that due to a faulty thrust bearing (covered under the non-mandatory technical service bulletin 25-NA-307), the entire engine sustained a catastrophic failure and that the engine “tanked itself” and “grenaded itself”. Driving with the reduced acceleration mode active is beyond frightening as it’s very difficult to navigate traffic intersections in time to avoid oncoming traffic. It was also noted that it other cases where this faulty part causes the engine to totally fail, the vehicle becomes unusable at that point. I was informed that a replacement motor is not expected from General Motors for at least 2-3 months as this is becoming a more prevalent issue with certain 2025...

Vehicle purchased 8/31/2025 October 20, 2025 "reduced acceleration" alert while driving on why up a significant grade with no way to pull off to the side of the road. Speed limitied to 35mph. Stopped by dealership pulled PO6DD code. Appointment made for November 12th. November 12, 2025 routine oil change and service noted "unable to duplicate concern on vehicly, currently no P06DD is present only DTC that was found in history was U1643 Lost communications with transmission control module can bus 2. cleared DTCs and test drove vehicle and is operating normal no issues. unable to duplicate." December 4th, 2025 driving on interstate and "reduced acceleration" alert...pulled into nearest dealer and code "P06DD" pulled. December 5th, 2025 returned to home dealership "Found Code P06DD. As per TSB#25-NA-307, checked the crankshaft end play, found the crankshaft has excessive end play. This is an indication of a worn thrust bearing. As per...

Truck started with a knocking noise in the engine that developed into a grinding noise. Dealer Service Department inspected and did a transmission tear down only to discover the issue is with the excessive play in the crankshaft. At 13K miles, the service department has stated the entire engine needs to be replaced.

We were traveling when it went into limp mode slowing our speed way down. We got it to a dealership and they determined low oil pressure and metal in the oil. My vehicle only has 1185 miles on it.

I got 3200 miles on my 2025 gmc 1500 6.2 engine. The engine crash. Knocking. Skund like its going to jump out. Been at dealer in columbus. Since Thursday. No one touch it

The engine seized and locked up leading to a catastrophic failure of my three month old 2025 GMC Sierra Denali at approximately 3,181 miles. The engine, the 6.2L V8, was listed as a recall engine by GM for model years 2021-2024. My 2025 allegedly "passed inspection" yet had the same catastrophic failure. The vehicle engine made loud noises and it sounded like parts were breaking. The vehicle no longer starts and had to be taken via flatbed to the dealership where I was informed the engine had to be replaced.

- On 9/23/2025 while driving down the main street, the vehicle unexpectedly shut down (engine stopped running) and would not restart. The vehicle is currently at Elevation GMC (Boone ,NC) waiting to be diagnosed. - Safety was put at risk by the vehicle unexpectedly shutting down in the middle the of rush hour traffic and not being able to be moved. - When it is was towed into the dealership and explained to the service manager what happened; she said "there is a known problem with the gear select lever losing communication with the truck and not knowing what gear it is in". - As of 9/24/2025; dealership has not looked diagnosed what the problem is/was. - There were no prior warning messages before the engine shut down.

I purchased a 2025 GMC Denali a few months ago. At approximately 7,000 miles, the front brakes failed unexpectedly and were replaced by the dealership. However, by 14,000 miles, I began experiencing brake issues again. Before I could return the vehicle for service, I was driving on the turnpike when the engine suddenly seized without warning. This created an extremely dangerous situation—vehicles behind me nearly collided as I lost power and control. I managed to pull over safely, but the tow truck operator struggled to load the vehicle due to all four wheels locking up and the engine being completely seized. Once the vehicle was inspected at the dealership, I was informed that the engine had failed and would need to be replaced. I am aware of the recurring issues associated with the 6.2L GMC engines and related component failures, and I no longer feel safe driving this vehicle. Given...

I’m filing this safety complaint in addition to a previous complaint, 11678151. which occurred on August 1, 2025. On Friday, August 22, 2025, I experienced a 2nd Traction Control alert and engine failure lights on my 2026 Sierra Denali Ultimate truck which again caused the acceleration to drastically decline while driving home from work. Thank God my kids were not in the car with me this time.  I am extremely appalled and confused as I've NEVER experienced this level of substandard operation from a new vehicle. I have informed the leadership team team at Cavender GMC West San Antonio, TX of the situation. The dealerships recommended (2) paths to exit the vehicle: GMC Customer Assistance and dealership trade-in.

The contact owns a 2025 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle experienced a loss of automotive power. No warning light was illuminated. The vehicle was towed to a local independent mechanic, where it was diagnosed and determined that the engine had seized and needed to be replaced. The local dealer was contacted. The vehicle was not diagnosed or repaired. In addition, the contact related the failure to an unknown recall; however, the VIN was not under recall. The manufacturer was made aware of the failure. The failure mileage was approximately 75,000.

While in the parking lot of a local grocery store, I shifted the vehicle into reverse, at which point all dashboard warning lights immediately illuminated and the braking response became significantly weakened and nearly unresponsive. I placed the vehicle back into park, paused, and then attempted to shift into reverse again, but the dashboard alerts and brake issue persisted. This created a very unsafe driving situation because the brake system was very unresponsive. Despite the unsafe condition, I cautiously drove to my home 2miles away at a speed of under 20 MPH, requiring excessive brake pressure to bring the vehicle to a stop. I parked the vehicle in my driveway and left it there overnight. The next morning, I tested the brakes, and they seemed to return to normal so I drove 5 miles to my local GMC service center. Service Tech confirmed Check Engine Light On and reported code...

The contact owns a 2025 GMC Sierra 1500. The contact stated while driving approximately 4 MPH and turning left into a parking spot, the vehicle independently accelerated. The contact stated that the brake pedal was depressed. The contact stated there was no warning light illuminated. The contact stated that the failure was intermittent, but the failure occurred while slowing down under 5 MPH and turning to the left. The contact had taken the vehicle to a local dealer; however, the failure was not duplicated. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 17,000.

The vehicle was purchased for the express purpose of towing a 6,600 lbs Travel Trailer. This truck is equipt with the 3 liter Diesel engine. While towing the truck computer counts down milage available based on Def level. The count down is not mile for mile it is an exponential count down. This factor triggers a series of warnings concerning vehicle operation and impending speed restrictions. 1000 mile DEF range warning is first up. Followed shortly there after with a 300 mile DEF range warning (700 miles had never been reached to trigger the warning). The next warning is "DEF Low (red warning) speed restricted soon". Shortly there after a 500 mile count down starts for the first impending speed reduction to 65 MPH max. This is followed by other speed restrictions that will put the vehicle eventually into a 5 MPH speed restricted mode. When adding DEF to the...

I WAS DRIVING ON A PA ROAD AT ABOUT 30 MPH. MY CAR STOPPED IMMEDIATELY AND I HEARD THE MOTOR REV. THE CAR THEN SLAMMED INTO A STOP.

Purchased the vehicle 300 miles away. Flew out, picked up the truck and drove it home. Got back Saturday night. Woke up Sunday morning to review the features, etc. Noticed a major oil leak. Called the dealership I purchased it from. They told me to take it to a (local) dealership. I took it to my local dealership. They looked at the vehicle. Initially they thought it was a faulty valve cover gasket. They ordered the parts. When they actually started taking the vehicle apart, the issue was not the valve gasket but the crack in the valve cover itself. They replaced the valve cover. It went to the dealer on date 03/03/2025 and they gave he vehicle back to me on 03/21/2025. They said this crack had to of happened on the production line but before it got delivered to the initial dealership.

While on the freeway at 65mph the truck experience a hard gear shift, loss of acceleration, went into shut down, lost steering assist, and brakes became hard, lights came on the dash for transmission issue massage, as well as Check engine light. Safety became a major concern with loss of power in the mids of a flow off traffic at freeway speeds. Vehicle had to be towed.