Most common 2021 GMC Sierra 3500 problems
Share of the 20 complaints; one complaint can involve more than one system. "~" is the median mileage when the problem started.
GMC Sierra 3500 complaints by model year
Best Sierra 3500 years: 2012, 2014, 2013. Years to avoid: 2024, 2020, 2023, 2025, 2022. Compare all years →
2021 GMC Sierra 3500 recalls (5)
Power train › Automatic transmission › Fluid/lubricant › Valves/valve body
General Motors, LLC (GM) is recalling certain 2020-2022 Chevrolet Silverado 1500, 2500, 3500, GMC Sierra 1500, 2500, 3500, 2021 Cadillac Escalade, Escalade ESV, Chevrolet Tahoe, Suburban, GMC Yukon, and Yukon XL vehicles equipped with diesel engines. The transmission control valve may fail and cause the rear wheels to lock-up.
Remedy: Dealers will install new transmission control module software, free of charge. GM will provide a special coverage program to cover the repair of transmissions that are identified by the remedy software as containing a…
Latches/locks/linkages › Tailgate › Latch
General Motors, LLC (GM) is recalling certain 2020-2024 Chevrolet Silverado 2500, 3500, GMC Sierra 2500 and 3500 vehicles equipped with power-unlatching tailgates. The tailgate's electronic gate-release switch may short circuit due to water intrusion, which can result in the tailgate inadvertently unlatching while the vehicle…
Remedy: Owners are advised to check that the tailgate is closed and latched before driving. Dealers will replace the exterior touchpad switch assemblies, free of charge. Owner notification letters were mailed May 17, 2024.
Service brakes, hydraulic › Power assist › Electric › Control module
General Motors, LLC (GM) is recalling certain 2021-2022 Chevrolet Silverado 2500, Silverado 3500, GMC Sierra 2500, and Sierra 3500 vehicles with electronic brake control modules (EBCM) replaced during vehicle assembly.
Remedy: Owners are advised to park outside and away from other structures until the recall repair is completed. Dealers will replace the BPMV assembly, free of charge. Owner notification letters were mailed on October 20, 2021.
Seat belts › Critical fasteners
General Motors, LLC (GM) is recalling certain 2020 Chevrolet Bolt EV and 2021 GMC Canyon and Sierra 1500, 2500 and 3500, Yukon, Yukon XL, Cadillac Escalade and Escalade ESV and Chevrolet Blazer, Camaro, Colorado, Equinox, Silverado 1500, 2500 and 3500, Suburban and Tahoe vehicles.
Remedy: GM will notify owners, and dealers will replace the suspect bolts, free of charge. The recall began January 29, 2021. Owners may contact GMC customer service at 1-800-462-8785, Cadillac customer service at…
Seat belts › Critical fasteners
General Motors, LLC (GM) is recalling certain 2019-2021 Chevrolet Silverado 1500 and GMC Sierra 1500, 2021 Chevrolet Suburban and Tahoe and GMC Yukon XL and 2020-2021 Chevrolet Silverado 2500 and 3500 and GMC Sierra 2500 and 3500 vehicles.
Remedy: GM will notify owners, and dealers will inspect left-side and right-side front-row center seat-belt bracket attachments and reassemble it correctly as necessary, free of charge. The recall began January 26, 2021.
NHTSA defect investigations
Federal safety investigators have looked into a possible defect involving the 2021 GMC Sierra 3500:
Air Bag Malfunction
On April 9, 2021, the Office of Defects Investigations (ODI) opened PE21-010 to investigate instances of air bag malfunction indicator light (MIL) illumination and potential for frontal air bag non-deployment in several vehicles manufactured by General Motors (GM).
What 2021 GMC Sierra 3500 owners say
Transmission & drivetrain
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. …
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. …
Brakes
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 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.
Electrical system
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.
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.
Frequently asked questions
Is the 2021 GMC Sierra 3500 a good car?
Based on 20 owner complaints filed with NHTSA, the 2021 Sierra 3500 rates use caution: 2.6× as many complaints as a typical year of the Sierra 3500 at the same age. It is one of the Sierra 3500 years we suggest avoiding. Complaint counts don't account for sales volume or individual maintenance, so have any used car inspected before buying.
What is the most common problem with the 2021 GMC Sierra 3500?
The transmission & drivetrain — 7 complaints, 35% of all complaints for this model year. Next are the brakes (5) and electrical system (4).
How many recalls does the 2021 GMC Sierra 3500 have?
There are 5 recalls for the 2021 GMC Sierra 3500, the most recent from October 24, 2024 (valves/valve body). Recall repairs are free at any authorized dealer — check whether yours has been done with the VIN recall check.
What are the best and worst years of the GMC Sierra 3500?
The best years by complaints, compared at the same age, are 2012, 2014 and 2013. Years to avoid or approach with caution: 2024, 2020, 2023, 2025 and 2022. See the full GMC Sierra 3500 years comparison.
At what mileage do 2021 GMC Sierra 3500 problems happen?
The median mileage reported in complaints is about 133,000 miles; 25% of problems with a recorded mileage started before 50,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.