My truck has been exhibiting hard downshifting at certain speeds, when the powertrain loads up such as a grade change, and requires a downshift. I have complained about this issue to the dealership as early as 2022, and 33,185 miles. The dealership made me pay for a transmission $388.90 flush which did not resolve the issue. The problem has become progressively worse, to the point where the toll road transponder fell of my windshield during a recent harsh downshifting incident. At the same time there was an existing MIL and derating for a DEF heater and NOx sensor failure, so during a warranty visit I asked that this transmission issue be addressed. On Friday March 13, the dealership called and said they confirmed the hard downshifting, albeit not as extreme as I described. The technician said that the valvebody needs to be replaced. At the same time, they performed a TCM flash for the 10L1000 momentary wheel lockup recall. The dealership then said they could not get the truck to set a P0747 code, said that GM refuses to replace the faulty valve body, and recommended I take the vehicle home unrepaired, and to come back when the P0747 code is set. I requested they continue to drive the vehicle. Today March 20 the dealership called and said they could not get the code to set, and that I need to drive the truck and come back when the code appears, despite the truck exhibiting clear symptoms of a progressively wearing feed limit low valve. N242454441 does NOT seem to indicate a P0747 code is required to replace the valve body. This vehicle is not safe for towing a 20,000+lbs and GMC is refusing to repair a transmission with symptoms congruent with N242454441. The dealership still has possession of the vehicle and wants $360+ in diagnostic labor.
The worst 2020 GMC Sierra 3500 problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
- Transmission19
- Electrical9
- Brakes7
- Engine7
- Fuel system6
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
- Transmission19
- Electrical9
- Brakes7
- Engine7
- Fuel system6
- Body5
- Tires4
- Driver assistance2
- Visibility2
- Airbags1
- Lights1
- Locks1
- Steering1
- Wheels1
Recalls 8
Power train: automatic transmission: fluid/lubricant: valves/valve body
- What is wrong
- General Motors, LLC is recalling certain 2020 Chevrolet Silverado 2500, 3500, GMC Sierra 2500, 3500, and 2020-2022 Chevrolet Silverado 1500 and GMC Sierra 1500 vehicles that may have been repaired incorrectly under recall 24V797. The transmission control valve may fail and cause the rear wheels to lock up.
- Risk
- Rear wheel lock up increases the risk of a crash.
- Remedy
- Dealers will inspect the vehicles and update the transmission control software, free of charge. Owner notification letters were mailed March 6, 2026. Owners may contact GMC customer service at 1‑800‑462‑8782 or Chevrolet customer service at 1‑800‑222‑1020. GM's number for this recall is N252516560. Vehicle Identification Numbers (VINs) involved in this recall became searchable on on February 12, 2026.
Recall number 26V083000 · Recall details
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
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
Air bags: side/window: curtain: inflator
- What is wrong
- General Motors, LLC. (GM) is recalling certain 2020 Buick Enclave, Cadillac XT5 and XT6, Chevrolet Blazer, Silverado 1500, 2500 and 3500 and Traverse and GMC Acadia and Sierra 1500, 2500 and 3500 vehicles. The diffuser component of the Roof-Rail Air Bag (RRAB) inflator may not have been properly crimped to the inflator and could separate from the inflator during air bag deployment.
- Risk
- If the diffuser separates from the inflator during deployment, RRAB performance may be degraded, increasing the risk of injury in a crash.
- Remedy
- GM will notify owners, and dealers will replace the suspect RRAB modules, free of charge. The recall began September 3, 2020. Owners may contact Chevrolet customer service at 1‑800‑630‑2438, Cadillac customer service at 1‑800‑333‑4223, or Buick customer service at 1‑800‑521‑7300. GM's number for this recall is N202305380.
Recall number 20V446000 · Recall details
Latches/locks/linkages: hood: latch
- What is wrong
- General Motors LLC (GM) is recalling certain 2020 Chevrolet Silverado 2500 and 3500 and GMC Sierra 2500 and 3500 vehicles previously recalled under 20V‑142. Some of the vehicles in 20V‑324 were not part of Recall 20V‑142 but received defect parts during another service (typically during collision repair). The hood-latch striker wires on replacement hoods installed for Safety Recall 20V‑142 may not have been heat-treated properly, possibly causing them to fracture.
- Risk
- If a striker wire fractures, the hood may open unexpectedly while driving, increasing the risk of a crash.
- Remedy
- GM will notify owners, and dealers will replace the hood assembly, free of charge. For hoods sold over the counter, dealers will contact customers with instructions for hood replacement. The recall began July 7, 2020. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑888‑988‑7267. GM's number for this recall is N202306490.
Recall number 20V324000 · Recall details
Latches/locks/linkages: hood: latch
- What is wrong
- General Motors LLC (GM) is recalling certain 2020 Chevrolet Silverado 2500 and 3500 and GMC Sierra 2500 and 3500 vehicles. The hood-latch striker wires may not have been heat-treated properly, possibly causing them to fracture.
- Risk
- If a striker wire fractures, the hood may open unexpectedly while driving, increasing the risk of a crash.
- Remedy
- GM will notify owners, and dealers will replace the hood assembly, free of charge. The recall began April 13, 2020. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑888‑988‑7267. GM's number for this recall is N192284960.
Recall number 20V142000 · Recall details
Seat belts: pretensioner
- What is wrong
- General Motors LLC (GM) is recalling certain 2019-2020 Chevrolet Silverado 1500 and GMC Sierra 1500, and 2020 Silverado 2500, Silverado 3500, Sierra 2500, and Sierra 3500 vehicles equipped with carpet floor covering. When the front seat belt pretensioners deploy, hot gas may vent through an opening in the pretensioner bracket, possibly igniting the carpet.
- Risk
- A vehicle fire could result if materials ignite inside the vehicle.
- Remedy
- GM will notify owners, and dealers will close off the opening in the pretensioner bracket, free of charge. The recall began December 13, 2019. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑888‑988‑7267. GM's number for this recall is N192270600.
Recall number 19V814000 · Recall details
See all 8 recalls for the 2020 GMC Sierra 3500
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 2020 GMC Sierra 3500 908
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
- 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
- This PI provides information to repair the door water deflector which is not sealed properly allows water...
- This PI provides diagnostic tips for diagnosing electric trailer brakes issues.
- PI to help diagnose A/C concern
What 2020 GMC Sierra 3500 owners say
Most recent owner complaints, unedited.
Diesel exhaust fluid tank heater malfunctioned and meted tank and connectors.
Known defect with 2019 and now 2020 GMC sierra trucks. Design was updated for 2021+ which has corrected the seal failure defect. GM has issued a service bulletin to dealers about how to repair the problem. Back window is leaking water. Defective seal noted by GM. GM is only covering the cost of repair if. Vehicle is still under 3/36 warranty. If outside your warranty cost from dealer to owner is $2500 to $6000. A known design failure GM recognized and took steps to change the design for future. Vehicles but will not stand behind vehicles that have this defect. Would like the cost to the repair fall back to GM to cover. Bulletin # 18NA383 [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
the engine seized at 65mph. available for inspection. was left stranded in a limited access area with no cell service. there was no warning, the engine just stopped at highway speed and would not restart. the problem was confirmed by an independent service center. they couldnt identify which component had failed without a costly teardown. occurred at 112,000 miles, past the 100,000 mile powertrain warranty.
The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently went into LIMP Mode. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed that the transmission valve body sensor had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and referred the contact to the federal safety agency Hotline for assistance. The approximate failure mileage was 130,000.
The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving at 60 MPH, the rear differential seized, in addition, the contact was hauling a median size tracker on top of a flat bed. The flat bed jackknifed and hit the left side of the contact's vehicle. The vehicle was able to come to a stop. The air bags did not deploy. There was no warning light illuminated. A police report was filed. There were no injuries sustained. The vehicle was towed to a towing yard. The trailer was towed to the residence. The tractor was damaged in the accident. The vehicle was diagnosed by an independent mechanic. The contact was informed that the transmission had failed. The vehicle was not repaired. The insurance company was contacted. A claim was filed with the insurance company, and it was canceled a few days later by the insurance company. The manufacturer was not notified of the failure. The failure mileage was approximately 108,000.
The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving 45 MPH with passengers seated in the rear seats, the passengers became aware that water was entering the vehicle between the window and frame. There were no warning lights illuminated. The vehicle was taken to the local dealer, who informed the contact of Technical Service Bulletin: 18-NA-383. The vehicle was not diagnosed or repaired. The manufacturer was contacted and confirmed that there was no special coverage or warranty coverage on the vehicle. The contact was referred to the federal safety agency Hotline for assistance. The failure mileage was approximately 50,000.
LT275/65R20 While driving Westbound on I87/US64/US264 at the on ramp of US64 business at highway speeds, the driver’s side rear tire tread de-laminated from the belts of the tire. Observed the entire tread airborne in rear view mirror. Pulled over to shoulder and observed for damage to other vehicles, no vehicle was hit but drivers did have to make evasive maneuvers to avoid debris. Tire remained at required PSI, thus did not deflate. Drove vehicle ¼ mile to ** exit to look for safe parking. Called AAA and had vehicle towed to residence. No police report filed. Reported incident to insurance agent in the event of a subsequent damage claim by other drivers. Tire was inspected by ** Tire and confirmed tread had indeed de laminated from tire core. Clear failure of factory tire mounted on factory wheels with no suspension or drive train modifications. Vehicle was totally stock at time of the incident. The safety of the other drivers on the road could have been significantly impacted had the tread hit their windshield or front tire. The violence of the tire separation was similar to an impact with large road debris. The vehicle suffered significant damage to the drivers side truck bed, bumper, sensors and wheel-well. Local tire company confirmed failure mode of tire. Vehicle had received required annual NC State safety inspection, by certified inspection station, including tires on April 30, 2025. There were no warnings prior to incident, visual or audio. The tire(s) involved are available for inspection, as owner has retained all 4 tires at time of replacement.
Engine started skipping, then service parking brake light came on, then service engine light came on and speed dropped to 44 mph.
My IntelliBeam function stops working sometimes, I can still use the lights as normal but the IntelliBeam function stops every so often and starts working after about 2 to 10 mins. Lane departure warning stops every so often and will start working after 1 to 10 mins, I have noticed that when it stops working at night time then the IntelliBeam function stops working also. When I press the on/off button for lane departure then it will say that lane departure is unavailable right now. I have been getting a p20ee code showing something is wrong with SCR nox sensor 2. Scan tool reveals that the sensor works normal and then stops. Once I clear the code then it works good for a few days.
Compare the 2020 GMC Sierra 3500
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Questions about the 2020 GMC Sierra 3500
Is the 2020 GMC Sierra 3500 reliable?
Owners have filed 51 complaints about the 2020 GMC Sierra 3500, 2.7 times a typical Sierra 3500 model year. It is one of the years we flag to avoid.
What is the 2020 GMC Sierra 3500 year score?
The 2020 GMC Sierra 3500 scores 30 out of 100 (poor). The score compares it with the other model years of the GMC Sierra 3500: 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 2020 GMC Sierra 3500?
Transmission and drivetrain, with 19 complaints. Next is electrical (9).
How many recalls does the 2020 GMC Sierra 3500 have?
8 recalls, covering power train, latches/locks/linkages and seat belts.
Was there a recall on the 2020 GMC Sierra 3500 transmission?
Yes, 2 recalls: 26V083000, 24V797000. Check your VIN to see if your car still needs the free repair.
What year does the GMC Sierra 3500 have bad transmission?
The GMC Sierra 3500 model years with the most transmission complaints are 2020 (19 complaints), 2023 (14 complaints) and 2024 (13 complaints).
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