GMC Sierra Complaints (2021)

671 consumer complaints on file.

#11733017April 22, 2026
UNKNOWN OR OTHER
XXX Power Assist Step Reversing I have a 2021 GMC Sierra 2500HD that the local dealership (Ozark MO 65714) is stating has expired and not covered by the warranty. I researched online and as I understand this recall falls under SAFTEY recalls and is to be fixed and doesn't expire? It requires no parts but the reprogramming of the K4 Assist Step Control Module. What is my next step or recourse?
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11732844April 21, 2026
UNKNOWN OR OTHER
Engine coolant control valve
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11732548April 20, 2026
ENGINE, UNKNOWN OR OTHER
Coolant control valve failing. Warranty not covering this part. Seems to be a manufactured issue. Happening on a lot of 2021 GMNC Sierras with the 3.0l Duramax.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11732123April 18, 2026
ENGINE
My L87 engine has failed due to a manufacturing issue. The recall number for this issue is N252494000. Upon contacting GMC, they state that my VIN number is not included in this recall despite having the same exact issues. I took the vehicle into a mechanic as soon as a problem had arose.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11731720April 16, 2026
ENGINE, POWER TRAIN, FUEL/PROPULSION SYSTEM
While driving into work, I noticed a knocking sound from the outside of the vehicle. Once parked, upon further inspection I narrowed down the area of the noise to the bottom rear of the engine/front of transmission. Fortunately, I was able to park in front of my office building and wasn’t stranded on the side of the road but under different circumstances it could've been the side of a busy highway or hours from home. I had the vehicle towed to the dealership I originally purchased from, the dealership was able to duplicate the issue with me present. Later that afternoon I was informed that the engine had failed and a replacement would be ordered. There was no prior indication of a problem or warning/CEL’s. The engine failed after the dealership had completed the engine recall ( pico test and 0-40W oil change ) related to the vehicle. I am reporting this in hopes that it helps with the investigation. This has been very disappointing for me as I have supported the brand of vehicle for many years. Only to have many issues under 80,000 miles and to lose confidence in the vehicle I purchased and the company.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11730861April 13, 2026
ENGINE, POWER TRAIN
The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 45 MPH, the transmission inadvertently shifted from drive (D) to first gear. The check engine warning light was illuminated. The vehicle was pulled over to the side of the road and then towed to the dealer, where it was diagnosed, and it was determined that the valve body needed to be replaced. The vehicle was not repaired because parts were not available. The manufacturer was notified of the failure. The failure mileage was approximately 103,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11730203April 9, 2026
ENGINE AND ENGINE COOLING
See attached document for complaint. INFORMATION, DETAILS, COMMENTS, DATES, AND NUMBERS ON RECALL 20211500 DENALI Recall Vehicle Information: All models of GM's with 6.2L gas engine (My personal truck I owned} • Recall date: April 23, 2025 650,000 + GM vehicles with 6.2L gas engine, years 2019-2023 • Manufacturer Recall Number: N2524944000 (letter issued by State of Washington Dept. of Licensing, PO Box 9020 Olympia, WA. 98507-9020 • NHTSA Recall Number: 25V274 • 2021 GMC 1500 Sierra Denali, x-tended cab, 4wh dr, 6.2 L gas engine • Vin #: WITH 6,400 MILES ON MY TRUCK May 15, 2025 • Went to local dealer, Becker Buick-GMC in Spokane, WA., to verify there was a recall on my truck and vin. #. Confirmed with there service department and sales person Jon Stone. • I was informed that the Dealership, service dept., and salesman Jon Stone, and Sales Mgr. Cameron could only say the following: "GMC DOES NOT have the tools made yet to verify if the engine will need to be replaced and would add me too the list and keep me posted." • I was informed at this time that t he issues with the engine were: engine could stop and start again at random; the engine start to smoke and stop; the engine could catch fi re whether it was running or not, or the engine could do ALL THREE things. • I was told to just keep driving the truck but watch for any of these issues. May 28, 2025 • Stopped in local dealer, Becker Buick-GMC, again to see if any updates. • Told GMC still had done nothing to develop the necessary tools to evaluate the engine and had no date to report or share with me on when they co uld. • Again, I was told to keep driving the truck and if I had a problem, Becker Buick would come and tow me. • Salespeople did ask if I wanted to just buy a new truck several times. They were impressed my truck only had 6400 miles on it and in such excellent shape. This was to be my retirement truck. June 5, 6, 7, 2025 • I visited several car dealers in the Spokane, WA. Area. Ford, Chevy, Dodge and Toyota. While looking at new/different vehic
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11729967April 8, 2026
ENGINE, POWER TRAIN
I have a 2021 GMC Sierra 1500 AT4 3.0L diesel pickup truck with 98,500 miles. The coolant control valve failed on my vehicle and for some reason it is not covered under GM's special bulletin that covers this part 15yr/150,000. Ridiculous.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11729289April 5, 2026
ENGINE
6.2 lifter failure at 44500 miles
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11729049April 3, 2026
ENGINE, FUEL/PROPULSION SYSTEM
Began with a misfire on cylinder 5 code P0305. Replaced spark plugs, wires, and coil pack. Misfire still existed. Fuel injector on cylinder 5 was stuck open and had to be replaced. Misfire still existed. No spark from new coil pack on cylinder 5, replaced coil pack connector. Misfire still existed, but lifter tick became present. Removed cylinder head and found exhaust lifter on cylinder 5 was bad and needed replaced. Currently awaiting parts delivery (only available through GM dealer). Have been without vehicle for 7 weeks now. Was told this was most likely related to Active Fuel Management.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728421April 1, 2026
ENGINE
THE ENGINE COMPLETELY SHUTS OFF WHEN I STOP AT A STOP SIGN OR STOP LIGHT. I HAVE BEEN STUCK IN TRAFFIC INTERSECTIONS ON SEVERAL OCCASIONS UNABLE TO MOVE WHEN THE LIGHT TURNS GREEN. EVENTUALLY THIS WILL LEAD TO ME GETTING REAR ENDED AND PUSHED INTO IN THE MIDDLE OF AN INTERSECTION. MY LIFE IS IN DANGER WHEN I DRIVE THIS VEHICLE. I GOT MY ENGINE REPLACED AND STILL THE SAME ISSUE IS OCCURRING WITH THE AUTO STOP AND START SYSTEM.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728444April 1, 2026
ENGINE
There is a recall on the 6.2 motor that is in my truck at my last oil change they performed a pico scoop diagnostic on the truck said it passed and gave it the new type of oil and oil cap that was suppose to fix it. Now a couple months later I walk out start my truck to let it warm up and after starting all of a sudden the engine started nocking bad and loss of oil pressure and on dip stick. I looked it up and this is what happens when the engine fails due to the massive recall on the 6.2 engines. I called the dealer and they are having me tow the truck potentially at my expense for them to look at and decide if it falls into the category of the recall after they did the test, and at one point told me that cause they did the test it is no longer recalled. I am being told people who have had the engines replaced because of the recall that the replacement engines have failed as well. I have a 9 month old baby and this left me stranded and unable to pick him up from daycare I had to scramble to find somone able to do so. I'm concerned that this could have happened while driving and having him with me or being left stranded somewhere.I'm glad it didn't happen when I was dropping him off that morning and while I was driving And meanwhile while they look at the issue and decide weather this falls under there recall or not and while it gets repaired I'm left without a vehicle and to be honest I don't feel safe even if they do repair it as there seems to not be an actual fix to the situation. this is unsafe and unacceptable for the price we have to pay for these rigs and the safety regulations and standards we have, how is this even an issue.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728447April 1, 2026
ENGINE
-The engine in my 2021 GMC Denali 1500 with the 6.2L engine failed its second engine with ~4,000 miles on the new engine. It is currently at GMC dealer waiting for a 3rd new engine. - Fortunately i was parked when the failure happened and the engine locked up. -Dealer confirmed that a valve dropped and damaged the cylinder wall. - There were no warning lamps or other indication that a failure was about to happen. -Current mileage ~91,000. First motor changed ~85,000 due to recall with previous owner.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728457April 1, 2026
ENGINE
The contact owns a 2021 GMC Sierra 2500. The contact stated that while driving at 55 MPH, the vehicle stalled unexpectedly. There were no warning lights illuminated. The vehicle was taken to the local dealer, where it was diagnosed, and determined that the engine needed to be replaced. The engine was replaced; however, the failure recurred. While at a stop and attempting to drive around a curve, the vehicle stalled. No warning lights were illuminated. The vehicle was taken to the local dealer, where it was diagnosed with engine failure. The vehicle was not repaired. The failure mileage was approximately 77,000. The VIN was not available.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728316March 31, 2026
UNKNOWN OR OTHER
P1098 code coolant control valve fail service bulletin N252508341 my vin not covered but same motor and same part !
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728402March 31, 2026
POWER TRAIN
I believe the torque converter is failing. While driving approximately 38 mph and also 48 mph up to 51 mph the vehicle have a vibration feeling like driving on a rumble strip. If you maintain the same speed, the vibration continues if you speed up, slow down, or let off the gas it goes away. There are so many detailed explanations on forums and social media from other customers experiencing the same problem, but not seeing any recall made by GMC.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11727719March 28, 2026
STEERING
Loss of steering, erratic steering control. Steering locks up
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11726627March 24, 2026
ENGINE, ELECTRICAL SYSTEM
The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 50-65 MPH on an incline, the contact believed that the transmission was slipping or there was a misfire coming from the engine. The contact stated that the vehicle failed to restart automatically after the engine AUTO Start/Stop system was engaged after a complete stop. Additionally, the contact stated that after driving for a while, the vehicle went into LIMP Mode. The check engine warning light and other warning lights were illuminated. The vehicle was taken to the dealer to be diagnosed. The contact related the failure to GM Campaign Number: N252515590 (Corroded Ground Strap); however, the dealer had informed the contact that the vehicle was not covered because the VIN was not included and there was no warranty coverage on the vehicle. The vehicle was not yet diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 75,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11726714March 24, 2026
POWER TRAIN
While driving on the highway at normal speed, my vehicle was operating completely normally with no warning lights, messages, or prior issues. Without any warning, the vehicle suddenly lost the ability to accelerate and felt as if it had been shifted into neutral. I immediately had to pull over to the side of the highway, as this created a dangerous situation with surrounding traffic. The vehicle had to be towed to a mechanic. Upon inspection, I was informed that a coolant line connected to the transmission had completely blew off, causing a rapid loss of transmission fluid and resulting in total transmission failure. I was told this was not due to a rusted or deteriorated clamp, but rather a sudden component failure. This vehicle has been meticulously maintained and I have owned it for less than one year. There were no prior symptoms, leaks, or warning signs leading up to this incident. This appears to be a sudden and unexpected mechanical failure, not caused by neglect or misuse. The loss of power while driving at highway speed posed a serious safety risk to myself and others on the road.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11726731March 24, 2026
TIRES, TIRES:TREAD/BELT
Tires are LT275/65R20. While driving on interstate at approximately the speed limit and low 80 degree temperatures in South Carolina with proper placard pressure tire inflation checked two days prior, the truck developed a faint vibration which got worse over three or four miles. I slowed my speed and pulled over at next offramp and visually inspected truck for signs of vibration. Including looking over tires. It seemed like a drive line issue, however truck is a 2021 model with only 38,000 miles. After I could not find anything out of place I got back on the interstate to see if problems still existed. I was only traveling at 45 mph and vibration was getting worse, so I tried to slow and make it to next offramp when the driver side tire blew out causing me to have to quickly react to prevent having an accident. The tire tread and multiple parts of the truck inner fender guards and liner were thrown out into traffic and truck bed side is badly damaged. Prior to blow out there were no warnings on the dash board to to indicate any sort of issue and I verified tire pressures when I stopped after the vibration initially set in. The TPMS system was working properly at the time of the blowout. I have the tire if further inspection is warranted. My safety was at risk when tire blew out on the interstate along with vehicles traveling around me to avoid hitting the flying debris and tire tread. Further this was driver side tire and I had to change the tire on the side of the interstate with traffic right beside my vehicle. I called GMC and they said they would do nothing to help because they see tires as a maintenance item and truck is out of warranty period. I am a mechanical engineer having worked many years for major tire company as a tire design engineer. I am very familiar with load ratings, tire wear, life expectancies, and I believe theis tires failed prematurely. I bought this truck new and have always had tires properly inflated a never overloaded.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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