The contact owns a 2021 GMC Sierra 2500 equipped with Goodyear Tires, Tire Line: Wrangler Trail Runner, Tire Size: LT275/65R/20, DOT Number: N/A. The contact stated that while driving approximately 70 MPH, there was a loud booming sound coming from the driver’s side and the TPMS warning light was illuminated. After stopping to inspect the vehicle, tread separation was discovered on the rear driver’s side tire, but the tire remained fully inflated. The spare tire was mounted onto the vehicle, and the vehicle was driven from the scene. During the failure, the vehicle sustained damages to the driver’s side, bumper, and rear fender. The fully inflated tire was taken to the local dealer, and the contact was informed that the tire was sent to the manufacturer for inspection. The contact was later informed by the manufacturer that no assistance would be provided, and the failure was caused by road hazard, causing the tire to lose air pressure. The contact stated that after the failure, the tire had not lost air pressure and the tire was fully inflated when taken to the dealer. The failure mileage was 47,000.
The worst 2021 GMC Sierra 2500 problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
- Transmission13
- Lights9
- Engine8
- Brakes7
- Electrical6
- Body5
- Driver assistance4
- Locks4
- Airbags2
- Fuel system2
- Tires2
- Seat belts1
Specific symptoms reported on the 2021 GMC Sierra 2500
Recalls 6
Power train: automatic transmission: fluid/lubricant: valves/valve body
- What is wrong
- 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.
- Risk
- Rear wheel lock-up can increase the risk of a crash.
- 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 defective control valve. Owner notification letters were mailed December 12, 2024. Owners may contact GM customer service at 1‑888‑988‑7267, Cadillac customer service at 1‑800‑458‑8006, GMC customer service at GMC 1‑800‑462‑8782 or Chevrolet customer service at 1‑800‑222‑1020. GM's number for this recall is N242454440.
Recall number 24V797000 · Recall details
Latches/locks/linkages: tailgate: latch
- What is wrong
- 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 is in park.
- Risk
- An unlatched tailgate may open while driving and result in a loss of unsecured cargo, creating a road hazard and increasing the risk of a crash.
- 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. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑800‑462‑8782. GM's number for this recall is N232426400.
Recall number 24V060000 · Recall details
Service brakes, hydraulic: power assist: electric: control module
- What is wrong
- 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. The bolts that attach the brake pressure modulator valve (BPMV) assembly may not be properly tightened, which could fail to seal the two sub-assemblies and allow water intrusion.
- Risk
- Water in the BPMV may cause an electrical short circuit and increase the risk of fire.
- 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. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑800‑462‑8782. GM's number for this recall is N212349181.
Recall number 21V758000 · Recall details
Tires: temporary/emergency spare tire
- What is wrong
- General Motors, LLC. (GM) is recalling certain 2020-2021 Chevrolet Silverado 2500 and GMC Sierra 2500 vehicles equipped with a 17" spare tire (RPO ZHQ or ZXT) and either the 20" accessory road tire (RPO REM) or the 18" accessory road tire (RPO Q2V). Operating the spare tire with other 20" or 18" tires can prevent the Anti-Lock Braking System (ABS) from engaging.
- Risk
- An ABS system that cannot control the rear wheels independently increases the risk of a crash.
- Remedy
- Dealers will provide the appropriate spare tire and apply a new spare tire information label, free of charge. Owner notification letters were mailed on October 18, 2021. Owners may contact Chevrolet customer service at 1‑800‑222‑1020; GMC customer service at 1‑800‑462‑8782. GM's number for this recall is N212329780.
Recall number 21V578000 · Recall details
Seat belts: critical fasteners
- What is wrong
- 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. Incorrect bolts may have been used at one or more fastening locations to secure the seat belts to the vehicle. If an incorrect bolt was used, the seat belt may not be properly attached to the vehicle.
- Risk
- If a seat belt assembly is not properly attached to the vehicle, the seat belt may not properly restrain an occupant in the event of a crash, increasing the risk of injury.
- 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 1‑800‑458‑8006, or Chevrolet customer service at 1‑800‑222‑1020. GM's number for this recall is N202322230.
Recall number 20V811000 · Recall details
Seat belts: critical fasteners
- What is wrong
- 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. The seat belt brackets may not be secured to the seat frame in the front-row center seating position.
- Risk
- If a seat-belt bracket is not secured, the seat belt may not properly restrain an occupant in the front-row center seat position, increasing the risk of injury in a crash.
- 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. Owners may contact GMC customer service at 1‑800‑462‑8782, Chevrolet customer service at 1‑800‑222‑1020. GM's number for this recall is N202314670.
Recall number 20V792000 · Recall details
See all 6 recalls for the 2021 GMC Sierra 2500
Defect investigations
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). The vehicles included model year (MY) 2020 through 2021 CT4 and CT5 passenger cars, Sierra and Silverado trucks (1500/2500/3500 models), XT4 and MY 2021 Escalade, Suburban, Tahoe, Yukon SUVs.Technical Service Bulletin (TSB) 21-NA-005, issued in March 2021, addresses air bag MIL illumination with diagnostic trouble codes (DTCs) B0001-1B or B0012-0D. It cites rust particles in the connection terminal interface of the driver air bag inflator housing as the cause of the air bag MIL illumination. Illumination of the air bag MIL under these circumstances may result in a non-deployment of the frontal driver air bag during a frontal collision and increased risk of injury to the driver.GM stated a correlation exists between production delays due to the pandemic shutdown and premature corrosion initiation on the surface of the air bag inflator housing, which, in some cases, caused rust development during a seven (7) month period of vehicle production. In the rare instance when a rust particle dislodges from the driver air bag inflator housing and enters the air bag connector prior to assembly, an intermittent resistance spike at the air bag connector may result. The condition generates excessive resistance in the air bag electrical system when the steering wheel horn cover is manipulated or the steering wheel is turned. This excessive resistance is momentary. A crash commanding air bag deployment would need to occur exactly when the momentary excessive resistance occurs. Thus, there is a very low likelihood the hazard will present a risk during a crash of sufficient severity to warrant a commanded deployment. This failure mechanism occurs early in life and results in an air bag MIL illumination that corresponds to a DTC warning the driver that the vehicle requires service. The vehicle's air bag remains functional while the MIL is illuminated, and the DTC is present.Once the connection of the driver air bag module to the clockspring is made at the plant, or at the dealership for service, there is no longer an opportunity for rust migration into the connection point. The connector is sealed and has gold terminals, eliminating the expectation of fretting corrosion. All subject vehicles passed standard corrosion validation testing for extensive corrosion with no issue of air bag non-deployment.There is a low rate of occurrence: 1.41 incidents per thousand vehicles (IPTV) for all related occurrences, and 0.04 IPTV for occurrences with a mention of visible rust and/or corrosion on the air bag inflator housing. The average occurrence mileage for the subject vehicles is approximately 2,100. Every occurrence related to the alleged defect experienced an air bag MIL illumination and there are no verified allegations of air bag non-deployment within all data sources.To date, there have been no reported fires, crashes, injuries, or fatalities related to this issue. In view of the low rate, and the nature of early-life failure, the high detectability of failures, and low potential hazard to drivers, this Preliminary Evaluation (PE) is closed. The closing of this investigation does not constitute a finding by the federal safety agency that a safety-related defect does not exist. The agency reserves the right to take additional action if warranted by new circumstances.Review the ODI reports cited above at under the following identification numbers: 11537927, 11528888, 11525020, 11521401, 11506057, 11493107, 11486767, 11441525, 11433146, 11425658, 11423440, 11385267, 11376429, 11373466, 11366995.
PE21010
Technical service bulletins for the 2021 GMC Sierra 2500 1,066
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- This service bulletin provides information about GM Accessories
- Unknown or other
- Unknown or other
- Beginning with 2026 model year production, the floor console/armrest lamp design was changed by removing...
- Unknown or other
- • Improvements to OnStar functionality.
- This PI provides Diagnostics tips on how the LIN bus works and how to diagnosis it.
- Unknown or other
- This document assists GM dealer technicians with diagnosing torque converter concerns to ensure torque...
- Unknown or other
What 2021 GMC Sierra 2500 owners say
Most recent owner complaints, unedited.
The contact owns a 2021 GMC Sierra 2500. The contact stated that while driving at an undisclosed speed, the transmission unexpectedly shifted out of first gear and the vehicle failed to accelerate as needed. The failure had occurred twice. The vehicle was towed to the dealer, who determined that the valve body needed to be replaced. The failure mileage was approximately 38,000.
The left rear internal "top-hat" parking brake shoes suffered a total manufacturing bonding failure, causing the friction lining to completely delaminate and detach from the metal backing plates inside the rotor hub. This triggered Diagnostic Trouble Code (DTC) C060B (Left Park Brake Actuator Circuit). The failed components were replaced by the servicing facility and are unavailable, but the official dealer diagnostic scan sheet and itemized repair invoice are preserved and available for inspection upon request. Safety was compromised in two ways. First, the mechanical failure completely disabled the electronic parking brake system, forcing a heavy-duty truck to rely exclusively on the transmission's parking pawl to remain stationary. This creates a severe rolling vehicle hazard, especially on inclines or when hauling/towing heavy loads. Second, when these shoes disintegrate, the loose friction debris trapped inside the enclosed drum can shift, wedge, and cause a sudden mechanical wheel lockup or severe brake dragging at highway speeds, threatening vehicle control. The problem was officially confirmed and diagnosed by an authorized General Motors dealership service center. The technician scanned the vehicle, retrieved DTC code C060B, and confirmed upon inspection that the internal parking brake shoes had completely disintegrated. There were absolutely no physical symptoms, abnormal noises, dragging sensations, or brake pedal changes prior to the failure, as the parking brake shoes sit isolated inside the rotor hub. The issue appeared suddenly on May 23, 2026, when the vehicle immediately displayed a parking brake malfunction warning lamp on the instrument cluster dashboard and completely refused to engage the electronic parking brake.
After finishing a long drive south, I shut the engine off and a yellow engine code popped on. I connected my computer to it and revealed a P129F code (fuel pump control module). I have noticed that other GMC models have been included in a recall concerning this problem. The 2021 GMC 2500 Denali should be also since it is the same problem. This needs to be covered by the manufacturer since it is a constant problem.
I am reporting repeated failures involving both the transmission and diesel emissions (DEF) system on my 2021 GMC Sierra 2500HD Denali equipped with the 6.6L Duramax diesel engine and Allison 10-speed automatic transmission. While under warranty, the truck required replacement of the aftertreatment fuel injector and later the Reductant Control Module due to DEF/emissions system failures. General Motors also completed recall-related transmission software updates on the vehicle. At approximately 154,833 miles, the transmission began shifting improperly, set transmission fault codes, and required complete replacement at my expense. Less than 5,000 miles later, the vehicle again experienced a "Service DEF System" warning with multiple diagnostic trouble codes. Repairs required replacement of the DEF tank, DEF heater assembly, and NOx sensor. These repeated failures involve major drivetrain and emissions components on a heavy-duty truck. DEF system failures can place the vehicle into reduced-power (derate) mode, limiting vehicle performance and creating potential safety concerns while driving or towing. I am submitting this complaint so these failures can be documented as part of the federal safety agency's evaluation of similar vehicles.
We keep getting an error message that shows we need to service DEF SYSTEM, it also started to limit my MPH and is now locked at 55 MPH. initial check of the DEF SYSTEM shows a malfunctioning module. it has been happening over the last year to 18 months. they would reset it or it would sometimes go away on its own after having to drive it in order for the error to clear.
The contact owns a 2021 GMC Sierra 2500. The contact stated that on several occasions, the automatic power side-out step failed to extend as designed. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was 93,726.
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?
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.
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.
Compare the 2021 GMC Sierra 2500
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Other model years
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Questions about the 2021 GMC Sierra 2500
Is the 2021 GMC Sierra 2500 reliable?
Owners have filed 53 complaints about the 2021 GMC Sierra 2500, close to a typical Sierra 2500 model year.
What is the 2021 GMC Sierra 2500 year score?
The 2021 GMC Sierra 2500 scores 73 out of 100 (average). The score compares it with the other model years of the GMC Sierra 2500: 75 is a typical year, 50 means twice the usual complaints, and serious complaints and recalls lower it.
What is the most common problem with the 2021 GMC Sierra 2500?
Transmission and drivetrain, with 13 complaints, typically around 50,000 miles. Next is lights (9).
How many recalls does the 2021 GMC Sierra 2500 have?
6 recalls, covering power train, latches/locks/linkages and service brakes, hydraulic.
Was there a recall on the 2021 GMC Sierra 2500 transmission?
Yes, 1 recall: 24V797000. Check your VIN to see if your car still needs the free repair.
What year does the GMC Sierra 2500 have bad transmission?
The GMC Sierra 2500 model years with the most transmission complaints are 2024 (27 complaints), 2020 (25 complaints) and 2023 (21 complaints).
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