2021 GMC Sierra 3500 Owner Complaints

The contact filed the complaint on behalf of the owner of a 2021 GMC Sierra 3500. The contact stated that while the vehicle owner was driving at an undisclosed speed, the driver noticed that the rear wheels were attempting to lockup. The contact stated that the failure was noticeable while driving forward and while reversing. No warning light illuminated. The vehicle was taken to the independent mechanic, where it was diagnosed with detached rear brake pads and detached rear emergency brake shoes. In addition, the rear brake caliber had seized. The vehicle owner was informed that the rear brake pads and the rear emergency brake shoes needed to be replaced, and the rear brake caliber needed to be repaired. The vehicle was repaired. The dealer was made aware of the failure. The contact was advised to contact the NHTSA Hotline to report the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 140,606.

NHTSA ID

11743698

Incident

May 28, 2026

Mileage

140,606 mi

During takeoff the transmission acted as if it was in neutral while I was crossing traffic luckily, the semi truck that was coming towards me was able to stop. I had the vehicle towed to a shop. After the vehicle was towed to the shop the transmission acted normal when the mechanic searched the VIN number. There was a service bulletin issued by General Motors for this exact problem. Had the semi not been able to stop. It could’ve very well killed me or my children. I suppose if it would’ve killed someone, maybe general motors would finally do a recall for this very disappointed in general motors and the NHTSA, the fact that this is an ongoing problem and has not been fixed and as a customer, I was not even notified that this problem existed is very alarming.

NHTSA ID

11701315

Incident

Nov 21, 2025

The contact owns a 2021 GMC Sierra 3500. The contact stated that while his wife had the vehicle idling with the rear defroster activated, shortly afterwards, she observed smoke coming from the plastic on the rear sliding window. After a visual inspection, the contact's wife observed that the plastic was melting, prompting her to deactivate the rear defroster. No warning lights were illuminated. The vehicle was taken to the dealer, who was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 26,000.

NHTSA ID

11685740

Incident

Sep 1, 2025

Mileage

26,000 mi

The contact owns a 2021 GMC Sierra 3500. The contact stated that while reversing, the back over prevention camera screen displayed an image of the ground. The contact stated that the image was approximately ten feet behind the vehicle. The vehicle was taken to the dealer; however, the failure was not duplicated. The dealer replaced the back over prevention camera system, however, the failure reoccurred. The contact stated that the original back over prevention camera was installed in another vehicle, and the back over prevention camera system worked as designed. The contact was informed that the back over prevention camera was not the cause of the failure. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 70,000.

NHTSA ID

11680762

Incident

Jul 14, 2025

Mileage

70,000 mi

There is a known issue with these trucks with the infotainment screen blacking out, which renders the backup cameras inoperative. This is a huge safety risk and its astounding to me that this hasn't been recalled yet.

NHTSA ID

11660333

Incident

Sep 30, 2024

Vehicle is put into park after driving. Shift to Park warning comes on while vehicle is in park. Vehicle will not shut off due to this warning and must be left running unoccupied.

NHTSA ID

11647125

Incident

Feb 3, 2025

When carrying the electronic key in my pocket the vehicle will lock/unlock presumably due to the remote contacting other items in the pocket. I have owned well over a dozen GM vehicles and never had this issue. I believe the remote design has the lock/unlock buttons too proud of the surrounding surface

NHTSA ID

11647111

Incident

Jun 1, 2024

The contact's son owns a 2021 GMC Sierra 3500 Commercial Vehicle. The contact stated while her son was driving at an undisclosed speed uphill, the vehicle failed to shift to a gear higher than 5th gear. Additionally, the rear wheels locked up, causing the vehicle to come to a stop. The driver attempted to resume driving, but the vehicle failed to exceed 10 MPH. The contact was unsure whether a warning light had been illuminated. The vehicle was towed to the residence of the driver's girlfriend. The vehicle was then towed to the dealer, where it was diagnosed that the failure was related to NHTSA Campaign Number: 24V797000 (Power Train); however, the part to do the recall repair was not yet available. Additionally, the dealer informed the contact that the transmission needed to be replaced, but the part was not available. The vehicle was not repaired. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the failure and a case was filed. The failure mileage was approximately 133,000. Parts distribution disconnect.

NHTSA ID

11638908

Incident

Nov 10, 2024

Mileage

133,000 mi

Transmission had to be replaced from the dealership. Hard shifting dealership said truck was 23 days out of warranty. I couldn’t get into the dealership that truck was purchased from for 3 weeks. Had to go to the Jeff Gordon dealership, which is Chevrolet. And I had to replace the transmission.

NHTSA ID

11636808

Incident

Jul 29, 2024

Multiple instances of diesel engine emissions system parts and software failure. While driving, towing or not, the DIC would randomly display a message that the DEF level is low and reduced speed will occur in x-amount of miles and that mileage would then begin a visible countdown on the DIC, sometimes much more quickly than the actual speed I was traveling. In other words, it might at first state 500 miles remaining, but then be counting down from 500 miles by one mile per second of time, or faster. Each instance, I would park and attempt to refill the DEF tank, only to discover that the tank is already full or near full. My truck’s DEF tank has now been replaced twice under warranty with the latest tank being installed at only 35,460 miles on the odometer. During the latest replacement, the technician also diagnosed and replaced the electrical wiring harness related to the DEF tank, stating that one of the connector pins was not reading the required voltage. There was also a faulty diesel particulate sensor that was replaced under warranty. This emissions system is problematic, and it is unsafe to due to the drive ability restrictions it imposes due to faulty software and equipment. I use my truck to tow, and it would make for a very unsafe condition to have my vehicle’s speed become limited as if the vehicle ran out of fuel. Mountain grades. Two-lane highways. Passing through bad neighborhoods. Driving in uninhabited areas, sometimes late at night. Family of 6 in the vehicle. Unacceptable. General Motors Corp. must create a permanent and fail-safe fix for this emissions system and implement the parts. The emissions system warranty should be extended from 80k miles to Lifetime to cover the vehicles affected.

NHTSA ID

11623109

Incident

May 16, 2024

While driving 55mph on a 2 lane road, pulling a 5th wheel camper, the truck transmission downshifted by itself to a low gear. This caused a scary and immediate deceleration from 55 to 25mph. The trailer wanted to push into the oncoming lane the deceleration was so fast. The truck is at a dealership and they acknowledge the issue but not a fix other than putting back in the failed part. There was no warning and my readings say many others are having same issue. The small dealership we left the truck with (yemm Chevrolet in Galesburg Il) said they had 3 trucks with the same issue. The truck has been with the dealership for 7 weeks now.

NHTSA ID

11617429

Incident

Aug 9, 2024

When starting the vehicle, I got a message to service the parking brake (this is the second time I’ve had this warning appear in the 21,000 miles I’ve owned it, first was approximately 5,000 miles ago). When this warning is active the parking brake does not engage, and can’t be used to stop the vehicle when the brakes fail as they did today. With 42,774 miles on the vehicle, and the onboard monitor for brake wear showing remaining brake life at 94% front and 96% rear, brake fluid reservoir between Max and Min the brake pedal went soft and the vehicle would not stop. I resorted to putting the vehicle in neutral and pumping the brakes until the pedal got hard. As soon as I let off the brake my vehicle began to roll backwards, stepped on the brake pedal again and the pedal again went to the floor without stopping or slowing the vehicle (pumping the brakes got it stopped again inches away from running into my house). The myGMC app notified me that I need to service the ABS system. I had the vehicle towed to the dealership for diagnostics and repair. Possibly related, this afternoon before the brakes stopped working I felt a mild vibration when traveling 20-35mph that resembled the vibration that occurs when a wheel bearing has begun to fail. Tow truck driver witnessed the vehicles inability to stop when putting it in neutral to load vehicle. It is unimaginable that a vehicle can be placed on the highway that has no backup system in the event of brake failure. Had a kid run out in front of me there would have been no way to avoid the accident (no other warnings appeared to indicate the vehicle was unsafe to drive. Brakes worked correctly and stopped appropriately until they didn’t).

NHTSA ID

11584171

Incident

Apr 19, 2024

The right rear tire (Goodyear Wrangler 275/65R20) separated and blew out on the highway, the truck was very difficult to control however it was safely stopped and there were no injuries. There was no observed warning prior to the blow out. The tire separation caused damage to the right rear quarter panel. The spare was installed and finished the trip safely. A tire shop found a second tire with evidence of separation on the left front corner. The tire that blew out on the highway is (DOT PJOT JB1V 0721) and the other 3 including the one with evidence of separation is (DOT PJOT JB1V 0821). The blown tire has been returned to Goodyear in Ohio by the auto repair facility at Goodyears request. Goodyear is refusing to assess the other 3 tires unless I bring them to an authorized service center which is not possible with only 3 functional tires including the spare. The 3 remaining tires are at the auto repair facility.

NHTSA ID

11523697

Incident

Apr 30, 2023

Problem: Unable to shift transmission from D to another position like R, P, N due to snow/slush being on shifter. I travel on Idaho state highways and County roads that are plowed. In February, I traveled state highway 14. Road conditions were plowed snow roads, broken snow floor, slush and pavement without slush or snow. I had a passenger with me on this trip from Elk City, Idaho to Grangeville, Idaho via SH-14. When I pulled into my storage unit, I could not shift from D to P or N or R. I could only drive forward. The temperature in Grangeville was mid 40s. I did not have any tremendous snow build up on the under carriage or wheel wells. I drove to the dealer Gortsema Motors and their service technician said that I needed to go to a car wash and blow out the snow buildup next to the transmission linkage shifter. When I pulled into the car wash, I still could not shift the transmission. My passenger got out and used the water to push out the snow buildup around the linkage shifter. Then I was able to shift between all gears P, R, N, D. This is a big concern because this should not have happened. This is a major problem in the winter and had there not been a car wash to blow out the snow/slush, I would not be able to turn the truck off or restart the diesel truck in gear. There needs to be a protective shield around the shifter so that snow/slush does not get up into area and cause the shifter to not shift.

NHTSA ID

11459426

Incident

Feb 14, 2021

Part Number: 85138746 - DEF tank assembly, heater, pump, reservoir. I was told there were issues with the heater and pump. The heater turns high or the heater won’t work; and there are issues with the connector.02/24/22: My truck has 16,000 approx. miles. The check engine light came on and displayed message that I had so many miles until truck would be restricted to 65MPH. I took my truck into Kendall dealership in Nampa, Idaho and was told there was myself and another person who had the same issue. A couple weeks go by and I call the dealership back and was told that I was 5th in line and there were 20 behind me. I was told that there were 11,000 parts already spoken for and 6,000 parts on backorder. I was one of the backorder individuals. I was also told that they do not have a ETA on when they would receive parts and that parts show up unexpected. They told me that I would have to contact GM customer service for assistance. The dealer called me back March 31st to see if I got my camper moved and how much it cost to move. They told me the dealership would cover one month truck payment and would like me to send in my loan payment statement. I asked for clarification as I didn’t know how I could have been 2nd person and the other day he said I was fifth in line. He said that there are at least 2-3 persons for service technician at dealership. Only 2 got fixed in the last 2 months. I asked if the new part going in will have the same issue or will be a re-designed part that fixes the issue. Dealer said the same part. GM is working on a re-design part and not ready for manufacturing. I asked why this wasn’t on a recall and he said no because it would bring people in that don’t need it replaced because their part is still working, and that GM doesn’t have a re-designed part to fix the issue. Gortsema Motors in Grangeville, Idaho a friend brought in their 2018 Chevydiesel truck (with 87,000 miles) for the same issue. Dealer said they have many cases.

NHTSA ID

11459422

Incident

Feb 24, 2022

The throttle body gets stuck wide open after the eninge gets up to operating temperature, it will give some warning with the throttle like on off throttle use and no codes show up at all. The risk of everyones is in extrem DANGER. The break are to soft and well not stop unless you put both feet on the break pedal down to the floor. Tranismission can NOT figure out what gear it needs to be in way too many gears and horrible fuel mpg for the 6.6L Duramax L5P. None of the GM dealership will look at the truck unless there is a code or it is happening right there when they look up the trucks VIN.

NHTSA ID

11455361

Incident

Dec 10, 2021

•The diesel exhaust fluid heater is a faulty component in the system, there is a back order on the part with no ETA • My pickup only does 55MPH right now and soon to do 5MPH you cannot drive on a public road doing 5MPH •There is thousands of other people having the same exact problem! •The DEF light is illuminated on my dash along with the check engine light, when you diagnose the error code it comes up with “P20C1 Reductant Heater C Control Circuit/OPEN”

NHTSA ID

11454519

Incident

Feb 24, 2022

Tailgate falls open while traveling down the road

NHTSA ID

11446957

Incident

Jan 3, 2022

The vehicle recently had a recall repaired at the dealership. I subsequently took delivery on it as a BRAND NEW UNIT, and the brakes are extremely soft; to the point where I must depress the pedal to the floor to get it stopped even at slow speeds. I hoped it was just an air bubble from the repair; but the fluid levels are full and the dealer had no ideas on what could be wrong at this point. I have a great relationship with this dealer, and we’ll continue working on it. But GM is releasing absolute trash lately and I fear that some poor family will load up, trusting these vehicles, and be badly injured or killed. After 200 miles of driving it back to my residence, both at highway speeds and residential road speeds, these brakes have not improved; ruling out an air bubble. I’m worried it may be associated with the recall that was previously remedied.

NHTSA ID

11438295

Incident

Oct 26, 2021

Trailer brake wiring connection continually disconnectsthen reconnects some time later. Some periods of up to 10 minutes without having trailer braking power. Major safety issue when toeing fifth wheel trailer. We lost brakes going down steep grades. GMC is aware of issue, but has not provided a solution. Vehicle has been yo service shop with no resolution. Case has been opened with GMC.

NHTSA ID

11420443

Incident

Jun 10, 2021