2020 GMC Sierra 3500

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 NHTSA 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 nhtsa.gov under the following identification numbers: 11537927, 11528888, 11525020, 11521401, 11506057, 11493107, 11486767, 11441525, 11433146, 11425658, 11423440, 11385267, 11376429, 11373466, 11366995.

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.

NHTSA ID

11725965

Incident

Mar 12, 2026

Diesel exhaust fluid tank heater malfunctioned and meted tank and connectors.

NHTSA ID

11712433

Incident

Jan 12, 2026

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)

NHTSA ID

11693845

Incident

Oct 1, 2025

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.

NHTSA ID

11691992

Incident

Aug 28, 2025

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 NHTSA Hotline for assistance. The approximate failure mileage was 130,000.

NHTSA ID

11672242

Incident

Jul 9, 2025

Mileage

130,000 mi

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.

NHTSA ID

11672009

Incident

Oct 2, 2024

Mileage

108,000 mi

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 NHTSA Hotline for assistance. The failure mileage was approximately 50,000.

NHTSA ID

11670439

Incident

Jun 10, 2025

Mileage

50,000 mi

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.

NHTSA ID

11670235

Incident

Jun 27, 2025

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