Is the 2021 Gmc SIERRA 3500 reliable?

The 2021 Gmc SIERRA 3500 has 28 complaints filed with NHTSA (1.1x the segment average). Our reliability verdict: average. Most common issue: TRANSMISSION problems.

What are common problems with the 2021 Gmc SIERRA 3500?

Top problems: TRANSMISSION (7 complaints, avg repair $500); BRAKES (5 complaints, avg repair $500); ELECTRICAL (4 complaints, avg repair $500). Issues typically appear around 50K miles.

Are there any recalls on the 2021 Gmc SIERRA 3500?

Yes, there are 5 recall(s): SERVICE BRAKES, HYDRAULIC:POWER ASSIST:ELECTRIC:CONTROL MODULE, SEAT BELTS, SEAT BELTS, LATCHES/LOCKS/LINKAGES:TAILGATE:LATCH, POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE. Contact any Gmc dealer to verify if recalls have been completed on your specific vehicle.

How much does it cost to insure a 2021 Gmc SIERRA 3500?

Estimated US average full-coverage insurance for the 2021 Gmc SIERRA 3500 is approximately $1,687/year (sedan-midsize class). Actual quotes vary heavily by state, driver age, driving record, and credit — see the interactive insurance estimator on this page for state-specific pricing.

2021 Gmc SIERRA 3500

Problems, Recalls & Reliability Report

Average

Quick Summary

The 2021 Gmc SIERRA 3500 has 28 owner complaints filed with NHTSA — that's 1.1x the segment average of 25. The most common issue is transmission problems (25% of all complaints), specifically: •the diesel exhaust fluid heater is a faulty component in the system, there is a back order on the part with no eta • my pickup only does 55mph right now and soon to do 5mph you cannot drive on a public road doing 5mph •there is thousands of other people having the same exact problem! •the def light. There are 5 recalls issued for this model year.

Total Complaints

Recalls Issued

—/5

Safety Stars

1.1x

vs Segment Avg

Known Problems(top 5 of 8)

TRANSMISSION

7 complaints

25%

• •The diesel exhaust fluid heater is a faulty component in the system, there is a back order on the part with no ETA • My pickup only does 55MPH right now and soon to do 5MPH you cannot drive on a public road doing 5MPH •There is thousands of other people having the same exact problem! •The DEF light
• The throttle body gets stuck wide open after the eninge gets up to operating temperature, it will give some warning with the throttle like on off throttle use and no codes show up at all. The risk of everyones is in extrem DANGER. The break are to soft and well not stop unless you put both feet on t
• 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 paveme

Typical onset: 50K miles Est. repair: $500

“•The diesel exhaust fluid heater is a faulty component in the system, there is a back order on the part with no ETA • My pickup only does 55MPH right now and soon to do 5MPH you cannot drive on a public road doing 5MPH •There is thousands of other people having the same exact problem! •The DEF light”

— NHTSA complaint filing

Recalls (5)

SERVICE BRAKES, HYDRAULIC:POWER ASSIST:ELECTRIC:CONTROL MODULE29/09/2021

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. 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.

Fix: 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.

Estimated Insurance Cost for 2021 Gmc SIERRA 3500

Estimate only, not a quote. Modeled from NAIC + HLDI averages for a hypothetical 35-year-old driver with clean record + full coverage. Your actual quote depends heavily on your age, driving history, credit, ZIP code, and insurer.

Your state (affects local premium average)

Full coverage / year

$1,687

Full coverage / month

$141

Liability only / year

$611

vs US avg

+1%

How this estimate is calculated

US base full-coverage premium$1674

× state (US)1.00x

× vehicle class (sedan-midsize)0.96x

× theft risk1.00x

× safety rating1.00x

× vehicle age1.05x

= Full coverage estimate$1687

Coverage assumed: 100/300/100 liability + comprehensive/collision, $500 deductibles. Data sources: NAIC 2024 + HLDI loss studies.

Maintenance & Warranty

Recommended Gmc SIERRA 3500 Service Intervals

Oil change

8K mi / 12 mo

Tire rotation

8K mi

Brake fluid

36 months

Transmission fluid

45K mi

Engine coolant

150K mi

Spark plugs

100K mi

Cabin air filter

23K mi

Engine air filter

45K mi

Differential (AWD/4WD)

45K mi

Uses GM Oil Life System. Full-size trucks may have shorter differential and transfer case intervals if used for towing.

"Severe service" conditions (heavy towing, extreme temps, city stop-and-go) typically halve these intervals. Always consult your vehicle's owner's manual for the authoritative schedule.

Gmc New-Vehicle Warranty Coverage

Bumper-to-bumper (basic)

3 yr / 36K mi

Powertrain

5 yr / 60K mi

Hybrid/EV battery

8 yr / 100K mi

Corrosion (rust perforation)

6 yr / 100K mi

Roadside assistance

5 yr / 60K mi

These are the terms for a new Gmc. If you're buying a used 2021 SIERRA 3500, remaining coverage is usually pro-rated from the vehicle's original in-service date. Not all coverage transfers between owners — check with a Gmc dealer for VIN-specific remaining warranty.

Estimated Repair Costs

TRANSMISSION(~50K mi)

$500

BRAKES(~50K mi)

$500

ELECTRICAL(~50K mi)

$500

ENGINE(~50K mi)

$500

OTHER(~50K mi)

$500

Estimates based on average reported repair costs. Actual costs vary by location, shop, and severity.

🔍 Pre-Purchase Inspection Checklist

Based on 28 owner complaints for this specific year, here's what to check or ask about:

☐
TRANSMISSION: •The diesel exhaust fluid heater is a faulty component in the system, there is a back order on the part with no ETA • My pickup only does 55MPH right now and soon to do 5MPH you cannot drive on a public road doing 5MPH •There is thousands of other people having the same exact problem! •The DEF light
Typically appears around 50K miles. Repair cost ~$500
☐
BRAKES: 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 sol
Typically appears around 50K miles. Repair cost ~$500
☐
ELECTRICAL: 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 sol
Typically appears around 50K miles. Repair cost ~$500
☐
ENGINE: •The diesel exhaust fluid heater is a faulty component in the system, there is a back order on the part with no ETA • My pickup only does 55MPH right now and soon to do 5MPH you cannot drive on a public road doing 5MPH •There is thousands of other people having the same exact problem! •The DEF light
Typically appears around 50K miles. Repair cost ~$500
☐
RECALLS: Verify all 5 recalls have been completed — free at any Gmc dealer
☐
General: Get a pre-purchase inspection from an independent mechanic ($100-$200)