GMC TruckSierra 2500 HD2021Overview/gmc-truck/sierra-2500-hd/2021/base/

2021 GMC Truck Sierra 2500 HD

Factory specifications, fluid capacities, torque values, EPA fuel economy and the federal safety record for the 2021 Sierra 2500 HD.

The 2021 GMC Sierra 2500 HD sits within GMC's heavy-duty pickup range as a full-size truck purpose-built for demanding towing and hauling workloads. Service specifications for the model year call for 10.0 quarts of 15W-40 engine oil, a capacity that reflects the substantial powertrain packaging typical of this segment. Reliability tracking for 2021 records 49 total owner complaints with the power train cited as the leading area, accompanied by six recalls — figures that place this model year well above the nameplate's 2024 low of a single complaint and well below the 2015 peak of 147 logged across the Sierra 2500 HD's 1999-2026 reporting span. In the broader context of the truck's complaint history, the 2021 occupies a clearly middle position, signaling neither chronic trouble nor marked dependability for researchers weighing long-term ownership.

Model year2024202220212019

Quick specs

Fluid capacities, tune-up values and fuel economy at a glance.

Engine oil capacity10.0 qtOEM · verified
Engine oil type15W-40OEM · verified
Lug nut torque140 ft-lbsOEM · verified

Fitment & sizes

Replacement part sizes and factory part numbers — battery, bulbs, filters and belts.

From the factory this vehicle uses a BCI Gas: 94R; Diesel: 2 Batteries: 48; Auxiliary: 48 · Gas: 720; Diesel: 2 Batteries: 730; Auxiliary: 730 CCA battery, OE oil filter 12684038. Each part links to every other vehicle that shares it, so a part you already stock may fit more of your fleet than you'd expect.

Battery groupBCI Gas: 94R; Diesel: 2 Batteries: 48; Auxiliary: 48 · Gas: 720; Diesel: 2 Batteries: 730; Auxiliary: 730 CCAOEM · verified
Tire sizeLT275/70R18/E 125/122SOEM · verified
Wheel / rim8, DRW: 6.5 inOEM · verified

OE service part numbers OEM · verified

Engine oil filter12684038 alt 12731742
Engine air filter84121219 alt 84554703
Fuel filter13539108
Spark plug12622441
Battery88865934 alt 88866309
Front wiper blades84578275
Serpentine belt12658178 alt 12732707
Thermostat12680544 alt 89018168
Cabin air filter13508023

Service quick specs OEM factory data

Capacities, torques and tune-up values from the factory service manual.

This engine holds 10.0 qt of 15W-40 engine oil, Dot 3 brake fluid. Torque lug nuts to 140 ft-lbs. The firing order is 1-2-7-8-4-5-6-3.

Lubricants & capacities

Automatic Transmission FluidATF
Automatic Transmission Fluid Capacity14.37 qt
Automatic Transmission FluidATF
Automatic Transmission Fluid Capacity6.0 qt
Brake FluidDot 3
Brake Fluid Capacity2.11 pt
Engine Coolant Capacity30.1 qt
Engine Coolant Capacity15.5 qt

Engine torques

Crankshaft Position (CKP) Sensor Bolt(s)7.4 ft-lbs
Camshaft Position (CMP) Sensor Bolt(s)7.4 ft-lbs
Crankshaft Position (CKP) Sensor Bolt(s)18.0 ft-lbs
Camshaft Position (CMP) Sensor Bolt(s)18.0 ft-lbs
Engine Coolant Temperature (ECT) Sensor Bolt(s)24.0 ft-lbs
Engine Coolant Temperature (ECT) Sensor Bolt(s)15.0 ft-lbs
Oxygen (O2S) Sensor Bolt(s)31.0 ft-lbs
Knock Sense (KS) Bolt(s)18.0 ft-lbs

Chassis torques

Lug Nuts140 ft-lbs
Transfer Case Fill Plug15.0 ft-lbs
Transfer Case Drain Plug15.0 ft-lbs

Ignition

Cylinder Firing Order1-8-7-2-6-5-4-3
Cylinder Firing Order1-2-7-8-4-5-6-3
Spark Plug ManufacturerAC Delco
Spark Plug Gap.037-.043 in
Spark Plug Torque15 ft-lbs

Battery & A/C

RefrigerantR134a
Refrigerant Capacity1.40 lbs
Oil GroupPAG
Oil Capacity3.40 oz

Brakes

Brake Caliper Bolt to Carrier Torque55.0 ft-lbs
Brake Caliper Carrier to Hub Bolt Torque221.0 ft-lbs
ABS Sensor Torque6.7
Vented Rotor Minimum Thickness for ReplacementFront: 1.516
Vented Rotor Minimum Thickness after RefinishFront: 1.535
Variation from Parallelism Thickness Variation.001"
Maximum Rotor Runout.002"

Multi-step torque procedures OEM · verified

Front Wheel Hub — tightening sequence 1 stages

Prep Use a new retaining nut. Driveshaft Nut: Step 1: 244.0 ft. lbs., Step 2: Loosen 45°

3199.0
Connecting Rod (Large End) Bearings — tightening sequence 1 stages
126.0 ft. lbs., Step 2: 30°, Step 3: 30°, Step 4: 30°26 ft. lbs
Connecting Rod (Large End) Bearings — tightening sequence 1 stages
115.0 ft. lbs., Step 2: 85°15 ft. lbs
Cylinder Head — tightening sequence 1 stages
159.0 ft. lbs., Step 2: 90°, Step 3: Internal Short Hex Bolt: 40°, Step 4: All Except Internal Short Hex Bolt: 60°59 ft. lbs
Cylinder Head — tightening sequence 1 stages
159.0 ft. lbs., Step 2: 90°, Step 3: Internal Short Hex Bolt: 40°, Step 4: All Except Internal Short Hex Bolt: 60°59 ft. lbs
Cylinder Head — tightening sequence 1 stages
122.0 ft. lbs., Step 2: 59.0 ft. lbs., Step 3: 120°, Step 4: 24.0 ft. lbs.22 ft. lbs
Flex or Driveplate Bolts — tightening sequence 1 stages
111.0 ft. lbs., Step 2: 22.0 ft. lbs., Step 3: 45°11 ft. lbs
Engine Flywheel Bolts — tightening sequence 1 stages
159.0 ft. lbs., Step 2: 60°, Step 3: 60°59 ft. lbs

Factory maintenance schedule OEM · verified

Normal service, condensed from the factory interval matrix.

Under the factory schedule, replace the spark plugs every 97,500 mi; coolant at 150,000 mi. The big-interval services (at 150,000 mi for coolant, and the transmission fluid) are the ones owners most often skip — on a lower-mileage example, assume the original fluids are still in it and check them first.

Every 7,500 miAccelerator Pedal (inspect) · Body Latches, Locks & Hinges (lubricate) · Brake Shift Interlock Solenoid (inspect) · Brake System (inspect) · CV Joint Boot (inspect) · Engine Air Filter Element (inspect)
Every 15,000 miWindshield Wiper Blade (replace)
Every 22,500 miCabin Air Filter (replace) · Fuel Filter (replace)
Every 45,000 miEngine Air Filter Element (replace) · Fuel Evaporative Emission Control System (inspect)
Every 75,000 miHood Hinge (inspect)
Every 97,500 miSpark Plug Wires (inspect) · Spark Plugs (replace) · Transfer Case Assembly (drain & refill)
At 150,000 miAccessory Drive Belt (inspect) · Engine Coolant System (drain, flush & refill)

Reliability & federal safety record

Owner-reported issues, recalls, investigations and service bulletins on record with NHTSA — an unfiltered look at what owners actually experience.

Owner complaints about the 2021 GMC Truck Sierra 2500 HD lead in one area — the power train, 10 of 49 reports (20%), well ahead of the next concern. That matters, because the power train are also the target of recall 21V-758 on this vehicle — so the single most useful check before buying or servicing one is confirming it was actually performed. 4 of the reports describe a crash and 1 a fire — a small share of the total, but worth weighing against the power train pattern above. These are tallies of what owners actually reported to the federal government, not an editorial score — and higher-selling models naturally rack up more reports.

6
Open recalls
NHTSA campaigns
1053
Service bulletins
Manufacturer communications
1
ODI investigations
Office of Defects Investigation
49
Owner complaints
4 involved a crash · 1 a fire
Owner complaints by model year NHTSA · this generation & adjacent

Owner complaints filed with NHTSA, by component

All 49 complaints on record, top 8 components.

Power Train10
Exterior Lighting6
Service Brakes5
Engine4
Latches/Locks/Linkages4
Structure3
Electrical System3
Electrical System,Exterior Lighting2

Source: NHTSA Office of Defects Investigation complaint database.

Recalls NHTSA · verified

Showing 2 of 6 campaigns on record for this vehicle.

21V578000Tires:Temporary/Emergency Spare TireReported 29/07/2021

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"… 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…

21V758000Service Brakes, Hydraulic:Power Assist:Electric:Control ModuleReported 29/09/2021

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…

Technical service bulletins NHTSA · verified

Showing 5 of 1053 bulletins on record with NHTSA.

BulletinDateComponentSummary
PIT6473F2026-07-17Unknown Or OtherThis PI was created to help avoid unnecessary front camera module replacements
PIT65322026-07-06Unknown Or OtherThe purpose of this PI is to inform dealer technicians of a normal cab pressure relief…
PIT5544J2026-06-24Unknown Or OtherThis Preliminary information communicates information on a hydraulic rush type noise from…
PIT5966F2026-06-23Unknown Or OtherThis Preliminary information communicates an issue with an OTA pending message still…
PIT65232026-06-10Unknown Or OtherThis PI provides diagnostic steps for dealer technicians to verify the condition and…

Common OBD-II trouble codes

The most common OBD-II codes for this vehicle's emissions system. These are standardized SAE J2012 definitions, not vehicle-specific fault reports.

P0420
Catalyst system efficiency below threshold — Bank 1
P0300
Random / multiple cylinder misfire detected
P0171
System too lean — Bank 1
P0455
Evaporative emission system leak detected — large leak
P0128
Coolant thermostat below regulating temperature
P0442
Evaporative emission system leak detected — small leak

VIN tools

Decode factory build data for a specific vehicle by VIN.

VIN
Decode a VIN to confirm the transmission and build data for a specific Sierra 2500 HD. OEM
Build data
Plant, GVWR class, engine and body data for any 17-character VIN.
Recalls
Check open recall campaigns against a specific vehicle by VIN.

Vehicles with shared specs

Find every vehicle that shares this one's battery, bulbs, oil capacity, platform or parts.

Reference guides

Cross-vehicle references for the kinds of data on this page.

Frequently asked

How much oil does the 2021 Sierra 2500 HD take?

10.0 qt of 15W-40, per the factory manual.

Does the 2021 Sierra 2500 HD have open recalls?

NHTSA lists 6 recall campaign(s) for this model year. Check your specific vehicle by VIN.