2025 GMC Sierra 1500

One evening while driving home from work, the transmission warning light illuminated on my dashboard, indicating that the vehicle would soon stop. The notification specifically stated there was a transmission problem. The following morning, I brought my truck to GMC for service. After running a diagnostic, GMC confirmed an issue with the transmission. A few days later, GMC informed me that they were waiting for a replacement part to arrive. The part did not arrive for almost a month. During this waiting period, I was forced to pay for a rental car. Since my truck was still under warranty, GMC should have covered the cost of the rental car for the weeks my vehicle was awaiting repair.

On July 25, 2026 when starting my vehicle, it began to shake violently and I receive numerous errors, including a check engine light and displays in the infotainment, indicating there were engine and transmission errors with the vehicle. I received a text message notification and in app notification from GMC indicating that there was a critical error and provided error code P0352. This appears to be an error related to a faulty engine, this is the 6.2L V8, which is known to be problematic by GMC. Had this happened while I was driving on the interstate three minutes later, it could’ve resulted in great bodily harm or death to both myself and the general public around me. GMC was later able to reproduce the issue at the dealer, confirming the faulty equipment on the vehicle with less than 16,000 miles on it. The component was replaced by the dealer, however, the vehicle is available for inspection.

The engine shuts off while slowing down. It cuts off cleanly and the entire dash lights up and the transmission shifts to neutral. The driver display says to put the truck in park and hit the start button. After you do this the truck runs fine for about 2k-3k miles and does it again. I has done this 5 times within 10k miles. The dealer says nothing is wrong with the truck because the computer doesn't record any codes. This happens regardless of whether the auto stop/start feature is on or off.

Engine started making a loud knocking noise and it sounded like the engine was about to throw a rod. Turned engine off and called GM. Vehicle was towed to dealership and it was diagnosed with a thrust bearing failure. My truck only had 14k miles on it. To fix the bearing issue, it will need a new engine. GM does not currently have engines to replace the faulty ones so it has sat at the dealership for 3 weeks with No ETA as to when it will be fixed. This is apparently a common problem in the 2025-2026 models LZ0 3 liter diesel. They are still selling these affected vehicles currently, knowing that they may have a problem. GM needs to issue a recall and take these vehicles back.

Going down the highway at highway speeds engine fully seized up almost cause an accident,, totally locked up engine, got towed to dealer and they said total engine failure just like in the priare years., been waiting for a new engine for almost 3month due to these failing on other cars,, they will be replacing my old engine with same engine that in prone to locking up. only a matter of time till the new one does the same thing. i want a buy back but they say it has 70k miles and its over the warranty and they wont buy back

What component or system failed or malfunctioned, and is it available for inspection upon request? The engine/powertrain failed. The vehicle is a 2025 GMC Sierra 1500 equipped with the 6.2L V8 engine. The engine developed a severe knocking noise and loss of power at approximately 5,545 miles. The vehicle was taken to the GM dealership, where an engine replacement was approved. The failed engine/component may be available for inspection through the dealership or GM, depending on whether it has already been removed or returned to the manufacturer. How was your safety or the safety of others put at risk? The engine failure created a safety concern because the vehicle experienced reduced power/loss of propulsion while being operated. This could have put me and other drivers at risk because a sudden loss of engine power can make it difficult to safely maintain speed, merge, tow, or move the vehicle out of traffic. The issue occurred at very low mileage and without enough warning to prevent the failure. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. The problem was confirmed by a GM dealership. The dealer diagnosed the engine failure and GM approved an engine replacement under warranty. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? The vehicle was inspected by the GM dealership. GM was involved in approving the engine replacement under warranty. To my knowledge, the vehicle has not been inspected by police or insurance representatives. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? Prior to the failure, the vehicle developed a severe engine knocking noise and reduced power/lack of power. These symptoms appeared shortly before the engine failure at approximately 5,545 miles. I do not recall any specific warning lamps or messages before the failure, unless the dealership records

Either while stopping while driving or parking (forward or reverse) the engine RPMs go up thus wanting to move the vehicle in that direction causing the breaks needing to be applied harder. When you shift into neutral the RPMs go way up (3000). This has happened on this vehicle 3-4 times of which I have video of the latest occurrence. When put into R or D the RPMs are still over 1000. This also happened on the courtesy vehicle same make and model) I was given but on this one the RPMs went up to 5000 of which I also have a video. The dealership has not been able to duplicate the issue as of yet. My fear is that the vehicle will hit someone or something if the break isn't pressed to the floor. It happens very randomly. The dealer currently has my vehicle trying to figure it out. They say GM says there's nothing they can do. No warning lights or messages appeared.

Rough idle started at 11,400 miles. Took to GMC dealer near me and had thrust bearing clearance measured. Measured .0054"(within spec). They released truck back to me. 19,400 mile oil change found large metal(non magnetic) slivers in the filter media. I cut filters to check for issues due to known issues with this engine(metal). I called gmc corporate, i was told to not drive the truck. I paid out of pocket for the tow 142 miles away. Dealer told me they checked thrust bearing and came in at .0055", no noises, and no check engine light. Idle is very rough on start up. GM corporate stated a service advisor will call. Never got a call. I have sent and displayed the evidence and offered to show oil filter contents to both dealer and corporaten both have not done anything about this safety issue. This is a SEVERE safety issue. Engine is highly likely to lock up and cause serious injury to both me, my family, and others on the road. Dealer has released truck back to me and my family with clean bill stating they didnt find anything wrong. They refused to see my documentation of metal slivers or the 3 rimg binder full of maintenance records. As of now i will be escalating this to higher up in GMC corporate. SEVERE safety risk for my family and everyone on the road. GMC dealers refusing to diagnose.