2021 GMC Sierra 1500: complete transmission failure

Filed Sep 24, 2026 · Transmission · CA

I own a 2021 GMC Sierra 1500 AT4 with the 3.0L Duramax diesel. The vehicle developed severe transmission problems, including harsh/jerky shifting and a hard clunk when shifting into reverse. The vehicle was subsequently diagnosed with an internal transmission failure. The repair facility informed me that the transmission gears had failed and caused damage to the transmission and stated that the failure appeared to be related to a manufacturing issue. The repair facility also advised me to watch for a future recall because they believed this could be a widespread issue occurring in other vehicles. I am submitting this complaint so the failure can be documented and considered along with other reports of transmission failures involving this vehicle.NOTE FROM AUTOSHOP:TRANSMISSION FAILURE WAS DUE TO A MANUFACTURE DESIGN FLAW, NOT DUE TO THE CUSTOMER'S DRIVING HABITS. THE PUMP ORIGINAL DESIGN IS WITH SLANTED GEARS AND THE GEARS ARE FORCED AWAY FROM EACH OTHER AND PLACING TOO MUCH STRAIN THE BEARINGS ANI THE BEARING FAIL. AN UPDATE PERFORMED TO HAVE STRAIGHT CUT PUMP GEARS TO AVOID BEARING DAMAGE. CDF DRUM AND CENTER SUPPORT CHANGED TO UPDATED PARTS THAT ARE HEATED TREATED TO AVOID DAMAGE

Filed Sep 8, 2026 · Engine, Transmission · MA

Transmission failed, Value Body is listed by dealer as the cause. GMC is saying that my vehicle is not part of the recall, even though it is part of the same model, same years as well as the same problem, the value body on the transmission. See estimate from dealership Tucks GMC Hudson, MA TRANSMISSION REPLACEMENT WITH BYPASS VALVE $6800.00 RADIATOR REPLACEMENT LEAKING $1980.00 ABS TRACTION LIGHT WHEEL SPEED SENSOR $395.00 CHECK ENGINE LIGHT IS ON NEEDS PCV VALVE HOSE AND SOLENOID $430.00 OIL LEAK BETWEEN ENGINE AND TRANSMISSION ?

Filed Aug 28, 2026 · Transmission · NM

Rear wheel lock up. Very unsafe. I am on my 3rd valve body for my transmission. GM doesn’t want to replace transmission but will warranty for 150k miles. I bumped a semi during one of my lock ups.

Filed Jun 23, 2026 · Transmission · 65,561 miles · IA

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed, but the vehicle continued to move forward. There was no warning light illuminated. The vehicle was taken to the dealer and was diagnosed with transmission failure. The contact stated that the valve body and torque converter needed to be replaced. The dealer informed the contact that the transmission might need to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 65,561. The VIN was unavailable.

Filed Jun 16, 2026 · Electrical, Fuel system · TX

So I made an appointment to have my truck recalled and the Wednesday before I took it, and it cranked no start and I called the dealership. Ask if they had any other those like this and they said that it could be the fuel injector module and so I got it to a mechanic shop to read the codes and it gave me a code p062b and I asked the dealership to look into it and they never figured out what we were not wrong. I just testing the battery. Well, then I got it back after the recall was done and new transmission valve body put in and about 30 miles down the road it started to shake violently and had a flashing engine light so I got it home called the dealership the next morning because they were closed set up another appointment got it to the dealership dealership said it had a couple misfires but since it wasn’t over 100 they weren’t concerned even though I’m pretty sure it is related to the fuel model going out because it has been cranking rapidly whenever I try to start it, but they won’t do anything to figure out what’s wrong?

Filed Jan 20, 2026 · Transmission · MS

1-At approximately 40,000 miles, my transmission was replaced under warranty. It had been failing since approximately 2000 miles having a very hard time shifting between first and second gear. It was finally replaced at 40,000 miles. 2- At approximately 45,000 miles I took my truck into the dealership for this latest recall on the 6.2 L failure for inspection. Vehicle is inspected and I was told I would need to have an engine replacement. I was told that there was no ETA on when a replacement engine would be available and that I would be contacted when one was. Afterwards I was sent back home in the truck they just inspected for potential engine failure and said had a bad engine. As of now, I’m still waiting on a word of a new engine and my truck is still operating, but leaves me concerned that it could fail at any moment while driving it.

Filed Jan 15, 2026 · Electrical · MI

Truck went in service 9/17/2025 because the wheels locked up while driving. Transmission was replaced. Picked up truck and 2 hours later the truck shut off while driving and was started back up and was limp mode. Was told wire chaffing and they taped and rerouted wires. Picked truck back up and next day it did the same thing. Took back to the dealer and they said wires again. They taped wires back up and we picked up the truck. We had it 7 days and while driving down the expressway the whole truck shut off and would not start up again. Clearly that is a safety issue. After sitting on the side of the expressway for 10 minutes it started up again and was in limp mode and taken to the dealer again. I don’t know what has been done to it yet as they are not great at communication but they have had our truck for 4 months minus the 7 days we had it before it had to go back to the dealer.

Filed Oct 8, 2025 · Transmission · MN

Transmission on my vehicle has failed three times since I bought the vehicle in October of 2021. Vehicle currently has 39,000 miles. First transmission issue was resolved by the dealership by replacing the transmission valve body. This solved the problem for approximately 12,000 miles. In September of 2025 with 39,000 miles the transmission suffered a catastrophic breakdown which lead to complete transmission replacement. After being “fix” the vehicle suffered another catastrophic transmission failure within 400 miles of the complete transmission replacement. This incident caused the vehicle to shut completely down and I was stuck in the traffic lane of the US Highway. Fortunately my vehicle and I were not struck while waiting 30 minutes for a tow truck. Presently the vehicle is back at the dealership awaiting repair. From my review of available on-line information it appears there are 10’’s of thousands of GMC Sierra pickups with major transmission issues. This needed to be addressed before someone is killed due to the poor quality of these GMC trucks.

Filed Sep 19, 2025 · Transmission · OK

Transmission failure at a little over 120,000 miles while towing a side by side on the highway. This highway has a speed limit of 80 which is dangerous when the vehicle stops working properly for myself and any other drivers in itself. Earlier this year the transmission had been updated due to a recall and was deemed to work good by the dealership but didn’t notice any difference. Had an engine light pop up a couple hours before but no messages or any other signs to inform me of the issue and was still working fine with no struggle until it gave out

Filed Jul 30, 2025 · Engine · 20,000 miles · MI

The contact owns a 2021 GMC Sierra 1500. The contact received notification of the federal safety agency Campaign Number: 25V274000(Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The contact stated that while driving 30 MPH, there was an abnormal knocking sound coming from the engine compartment, and the vehicle lost motive power. The contact was able to pull over to the side of the roadway. No warning light was illuminated. The vehicle was towed to a dealer, where it was determined that the engine needed to be replaced. The vehicle was repaired. The contact stated that prior to the engine failure, the transmission was replaced. The dealer was contacted regarding the recall remedy, but the dealer was unable to provide an estimated time of availability. The contact stated that the manufacturer exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the failure. The failure mileage was approximately 20,000. VIN tool confirms parts not available.

Filed Jun 28, 2025 · Engine · NC

It started with a emergency brake light coming on, shortly (2 miles) later it started misfiring on cylinder #1 after replacing coil pack plug wire and plug. It then started smoking bad out of the exhaust. I knew GM was having recalls on the 6.2 engines so I hauled it to the dealer. They told me it was a bad engine and since it had aprox.62,000 miles on it and no recall it wasn't covered. Since then the dealer called the factory service rep. and he agreed to replace the engine at a 50% reduction in the price, but had no idea when they could get me a replacement engine. After a few days of research on my part I called the dealer again to get a price on how much it was going to cost me? The owner of the dealership ask me to give him a few more days to ask the rep. if he would agree to 100%. My problem now is I don't have it to drive, I can't sell it. and no idea how long it will be before it can be repaired. Plus I am still making payments on it. It is available for inspection at the dealer. If I had of continued to drive, it could have locked up causing a catastrophic accident. In my research it looks like these problems started in 2019 not late 2020 when mine was built. NC has lemon law complaints going back to 2019 that have been paid out. I currently own a #1 2007 GMC Yukon Denali 6.2 with aprox.389,000 miles and only replaced the transmission recently. #2 A 2008 GMC Sierra Denali 6.2 with 279,052 miles, new transmission. #3 A 2011 GMC Yukon Denali 6.2 with 234,361 miles and #4 a 2017 Cadillac Escalade 6.2 with aprox. 102,000 miles. All of these are working and driving on a daily bases. I have a lot of faith in these 6.2 engines until now, I will no longer be buying any more of these engines even though 1 out of 5 aint bad. Thank you for your consideration and for what you do. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed May 31, 2025 · Transmission · GA

Reached the 100,000 mile mark and the truck started shuddering. Took it to the dealership and they tell me the torque converter is coming apart and I need a new transmission.