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2021 GMC Sierra 2500HD SLE 4x4

The 2021 GMC Sierra 2500HD SLE 4x4 is a 401-hp 6.6-liter with a hydra-matic 6l90 6-speed automatic; final drive 3.73:1. and four-wheel drive.

It makes 401 horsepower and 464 lb-ft of torque.

The Sierra 2500HD measures 235.5 inches long on a 141.6-inch wheelbase and has a curb weight of 2,500 lb.

Spec Value
Vehicle
Body TypePickup
PowertrainGas
Price
Destination Charge$1,695
Engine
Engine Type6.6L V-8 gasoline OR E85 FlexFuel: cast iron block w/ nodular iron main caps, cast aluminum heads, 10.8:1 CR, OHV 2 valves/cylinder, VVT, direct injection.
Displacement6.6 L
Horsepower401 hp
Torque464 lb-ft
ValvetrainGas: overhead-valve, 2 valves/cylinder, variable valve timing (VVT). Diesel: overhead-valve, 4 valves/cylinder
Bore and Stroke103.25 x 98 (6.6L gas)
Compression Ratio10.8:1 (gas)
Injection TypeDirect fuel injection (gas)
Drivetrain
Drive Type4WD
Transmission
TransmissionHydra-Matic 6L90 6-speed automatic (6.6L gas); final drive 3.73:1.
1st Gear4.03
2nd Gear2.36
3rd Gear1.53
4th Gear1.15
5th Gear0.85
6th Gear0.67
Reverse3.06
Final Drive3.73
Fuel Economy
Recommended FuelRegular unleaded
Suspension
Front SuspensionShort-long arm (SLA) independent front suspension with torsion bars
Rear SuspensionSemi-elliptic three-stage multi-leaf spring
Brakes
Front Brake CalipersHydraulic power-assisted Hydroboost booster; four-wheel disc; ABS; StabiliTrak electronic stability control
Front Brake Disc14.0 x 1.6 in / 355 x 40 mm vented rotor (2500HD)
Rear Brake Disc14.1 x 1.3 in / 360 x 34 mm vented rotor (2500HD SRW)
Tires & Wheels
Wheels Front17 in. steel or aluminum (Regular, SLE std); 18 in. steel or aluminum; 20 in. aluminum (Denali std)
Wheels Rear17 in. steel or aluminum; 18 in. steel or aluminum; 20 in. aluminum
Tires FrontLT245/75R17 (ALS) / LT265/70R17 (AT) / LT275/70R18 (AT) / LT275/65R20 (AT)
Tires RearLT245/75R17 (ALS) / LT265/70R17 (AT) / LT275/70R18 (AT) / LT275/65R20 (AT)
Dimensions & Weight
Length235.5 in
Width81.75 in
Height79.94 in
Wheelbase141.55 in
Front Track68.1 in
Rear Track68.3 in
Ground Clearance10.19 in
Curb Weight2,500 lbs
Interior
Headroom Front43.11 in
Headroom Rear39.88 in
Legroom Front44.53 in
Legroom Rear35.24 in
Shoulder Room Front66.06 in
Shoulder Room Rear64.88 in
Hip Room Front60.9 in
Hip Room Rear60.24 in

Safety & Recalls

NCAP safety ratings

Tested, but no star ratings were published (2021 GMC Sierra 2500 PU/CC 4WD).

Recalls

6 recalls on file with NHTSA for the 2021 GMC SIERRA 2500. Not every recall applies to every trim or VIN — check yours at nhtsa.gov/recalls.

Oct 24, 2024 · POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE

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.

Consequence: 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.

NHTSA campaign 24V797000

Feb 1, 2024 · 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 is in park.

Consequence: 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.

NHTSA campaign 24V060000

Sep 29, 2021 · SERVICE BRAKES, HYDRAULIC:POWER ASSIST:ELECTRIC:CONTROL MODULE Park outside

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.

Consequence: 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.

NHTSA campaign 21V758000

Jul 29, 2021 · TIRES:TEMPORARY/EMERGENCY SPARE TIRE

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.

Consequence: 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.

NHTSA campaign 21V578000

Dec 23, 2020 · SEAT BELTS

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.

Consequence: 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.

NHTSA campaign 20V811000

Dec 17, 2020 · SEAT BELTS

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.

Consequence: 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.

NHTSA campaign 20V792000

52 owner complaints to NHTSA for the 2021 GMC SIERRA 2500

Owner Complaints

52 owner complaints filed with NHTSA for the 2021 GMC SIERRA 2500 (4 mention a crash, 1 a fire, 1 an injury). See all on nhtsa.gov

Most-cited areas
Power Train13
Exterior Lighting9
Engine8
Electrical System6
Service Brakes6
Structure5
A complaint can cite more than one area.
Most recent complaints
Oct 2, 2026 · Power Train
“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…”
Aug 5, 2026 · Service Brakes
“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…”
Jul 30, 2026 · Fuel/Propulsion System
“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…”
Jun 26, 2026 · Power Train, Engine, Fuel/Propulsion System
“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…”
Jun 1, 2026 · Power Train
“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…”

Complaints are unverified reports submitted to NHTSA by owners. They cover the whole model year, not a specific trim, and a count alone doesn't show how common a problem is.

Source: US National Highway Traffic Safety Administration (nhtsa.gov), matched as 2021 GMC SIERRA 2500. US-market vehicles only; data cached for up to 7 days.

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