2021 Chevrolet Suburban Powertrain (other) Problems

What component or system failed or malfunctioned, and is it available for inspection upon request? (On our 2021 gasoline suburgan, the rear wheels locked up at free-way speeds, which nearly caused a possibly fatal accident. The lock released but it appears the strain caused rear differential gear teeth to break and the rear differential now needs to be replaced for the vehicle to operate properly.) How was your safety or the safety of others put at risk? (The sudden rear wheel lockup at freeway speeds resulted in temporary loss of control of the vehicle and significant surprise to the driver, who, after swerving into the adjacent lane was able to gain control of the steering and stop the vehicle. Had there been another vehicle in the other lane the MVA could have been fatal for 9 people in the suburban and any other vehicle involved.) Has the problem been reproduced or confirmed by a dealer or independent service center? (The rear differential damage was confirmed by a dealer.) Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? (No.) Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? (No warning or messages. This has happened 3 times over 3 years, always on extended trips 9-12 hours in duration. The first two times nearly caused an accident but no differential damage. This third time, the differential was immediately damaged due to the incident. We have since learned that this is an issue with 2022 suburbans, for which a recall has been issued. A recall has also been issued for 2021 DIESEL suburbans. However, no recall has been issued to gasoline 2021 suburbans, but apparently needs to be.)

NHTSA ID

11750547

Incident

Jul 9, 2026

COMPONENT: The 10-speed automatic transmission failed on 6/29/26, locking the vehicle completely in neutral. The neutral override could not be disengaged even by dealership technicians. Vehicle is currently at [XXX] Chevrolet, [XXX] and is available for inspection. SAFETY RISK: I have 3 young children who are regular passengers. The failure occurred without warning. Had it happened at highway speed in oncoming traffic, I would have had no ability to move the car — creating a direct risk of a serious or fatal collision. CONFIRMED BY DEALER: Yes. Don Hewlett Chevrolet received the vehicle on 6/30/26 and confirmed the failure is directly related to two active federal recalls: NHTSA #24V-797 (10-speed transmission valve body failure/wheel lockup) and NHTSA #22V-036 (driveshaft assembly/loss of propulsion). Vehicle has been unrepaired for 13 days with no timeline provided. OTHER INSPECTIONS: Vehicle has been in possession of Don Hewlett Chevrolet since 6/30/26. No manufacturer representative, police, or insurance inspection has occurred. WARNING SIGNS: None. No warning lamps, messages, or symptoms appeared before the failure. The power train locked suddenly and completely without any prior indication on 6/29/26. Despite the dealer confirming this is recall-related, they have indicated I may owe partial repair costs. Under 49 U.S.C. § 30120, GM must remedy recalls at no charge regardless of mileage or warranty. I am requesting NHTSA investigate both the failure and GM's attempt to charge the owner for federally mandated recall repairs. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11750175

Incident

Jun 29, 2026

2021 Chevy Suburban started to have harsh shifting particularly on acceleration and shuddering at higher rates of speed (feeling like you are driving over a rumble strip). I took it to the dealer, and they confirmed the torque converter was in the process of failing. It's currently in the shop getting a new torque converter. No warning messages/lights had yet appeared. Technician at dealer stated that this was a common failure with this model.

NHTSA ID

11743773

Incident

Jun 1, 2026

The failure involved the transmission valve body control valve within the automatic transmission system of the 2021 Chevrolet Suburban, a critical component responsible for regulating hydraulic pressure and controlling gear shifting. The malfunction caused erratic and unreliable shifting behavior, including hesitation, harsh engagement, and loss of proper acceleration; the failed component is in the custody of Northside Chevy in San Antonio, TX. This issue created a significant safety risk, as the unpredictable transmission response impacted the driver’s ability to accelerate when necessary (merging onto high traffic roads) and increased the likelihood of dangerous situations like rear-end collisions or loss of control. The problem was confirmed by an authorized Chevrolet dealer, where diagnostic testing identified faults in the transmission control system and verified the failure through performance testing and fault codes. The vehicle has been inspected by the dealership service department, though it has not been directly examined by the manufacturer, law enforcement, or insurance representatives; however, documentation of the diagnosis is being withheld by the dealership. Prior to the failure there were no warning signs present. Only after failure did the check engine light illuminate, transmission-related warning messages, and noticeable symptoms such as hard shifting, delayed engagement, and slipping, which appeared shortly before the complete failure and significantly worsened over the three-mile drive to the dealership.

NHTSA ID

11742058

Incident

Jun 3, 2026

transmission failed high speed jerking shifting ruined a set of tires yes has been confirmed by dealer but our vin is not covered under the recall no yes error codes appeared before we took the vehicle in for service 6-5-2025 we have had the vehicle in to 2 separate dealerships a total of 4 times for repair now that powertrain warranty is expired they are calling for a transmission replacement

NHTSA ID

11740950

Incident

Jun 5, 2025

Suburban started to have shudder at lower rpm on acceleration. I took it to the dealer and they confirmed the valve is bad. They are unsure at this time but depending on damage from the bad value my Suburban may also need a new torque convertor or transmission.

NHTSA ID

11740036

Incident

Apr 10, 2026

The transmission of the 2021 Suburban failed. While operating the vehicle down a state highway, out of nowhere the power was reduced significantly while in traffic. It would not go over 30 MPH after forcing itself to 30 MPH while driving down the busy highway. After struggling to find a safe place to park, the vehicle would not, and still will not, go into reverse. There were no warning lights of any sort prior to this incident. Now there are several warning lights. The vehicle has been towed and taken to a repair shop with current unknown diagnostics as we are waiting our turn for the vehicle to be diagnosed. This vehicle has a transmission that is currently under Class Action for GM knowingly selling defective transmissions.

NHTSA ID

11735081

Incident

Apr 29, 2026

The contact owns a 2021 Chevrolet Suburban. The contact stated that while driving at an undisclosed speed, the vehicle jerked abnormally while shifting into reverse(R) or drive(D). The contact stated that the vehicle lost motive power with the check engine warning light illuminated. The contact was able to restart the vehicle; however, the failure persisted while attempting to drive. The contact also stated that the vehicle was put into LIMP Mode several times. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 78,000.

NHTSA ID

11732962

Incident

Apr 22, 2026

Mileage

78,000 mi

My 2021 Chevrolet Suburban experienced a sudden and complete engine failure at approximately 79,000 miles. The vehicle became inoperable and is currently at a dealership pending evaluation. There were no prior warnings indicating an imminent catastrophic failure. A sudden engine failure of this nature presents a significant safety concern, including the risk of loss of propulsion during operation. The failure has been confirmed by the dealership, and no repairs have been authorized at this time pending further review. This complaint is being submitted to document a sudden and severe engine failure and to request evaluation of potential safety-related defects involving internal engine components.

NHTSA ID

11726495

Incident

Mar 11, 2026

I am submitting this complaint to report a serious safety issue involving my 2021 Chevrolet Suburban equipped with the 3.0L Duramax diesel engine. The vehicle has experienced a recurring problem related to the engine wiring harness. While driving, the vehicle will unexpectedly stall without warning. At the same time, there is an immediate loss of power steering assist, significantly reducing the ability to safely control the vehicle. This creates a dangerous situation, especially at highway speeds or in traffic. The failure appears to be linked to a defect or malfunction in the engine wiring harness, which may be causing intermittent electrical interruptions to critical engine systems. There were no prior warning signs sufficient to prevent the incident. This issue poses a substantial safety risk not only to the driver and passengers but also to other motorists. Sudden engine shutdown combined with loss of steering assist increases the likelihood of a crash. I believe this may be a systemic defect affecting other vehicles of the same model and configuration. I urge the National Highway Traffic Safety Administration to investigate this issue and determine whether a recall should be issued. Vehicle Information: Make: Chevrolet Model: Suburban Year: 2021 Engine: 3.0L Duramax Diesel

NHTSA ID

11725782

Incident

Feb 7, 2026

On Friday, March 13, 2026, while traveling at approximately 60 mph on the highway, my 2021 Chevrolet Suburban equipped with an L87 6.2L V8 engine experienced a sudden and complete loss of motive power. The failure sequence began with a dashboard warning prompting me to "press the start button again," followed immediately by the vehicle shifting into neutral without any driver input. Despite repeatedly pressing the accelerator, the vehicle continued to decelerate and could not re-engage drive. A second dashboard warning displaying "engine recall" then appeared mid-incident. Subsequently, the rear wheels locked, forcing the vehicle to coast to a complete stop on the hard shoulder without any brake input required from the driver. Upon coming to a full stop, the start button continued flashing with repeated prompts to press it, the vehicle lock emblem illuminated on the dashboard, and the vehicle became fully and mechanically immobile, unable to shift out of neutral or transition into any other gear. The engine could not power the vehicle at all. My safety and the safety of other motorists were directly and seriously endangered, as the failure occurred without warning in the middle lane of an active highway at highway speed, leaving the vehicle unable to maneuver or accelerate out of harm's way. A responding police officer confirmed the road hazard on scene and remained present to protect the vehicle and occupants while we awaited assistance. The AAA tow truck operator independently concurred upon arrival. The vehicle was transported to Classic Chevrolet, Grapevine, TX, the same day and is currently awaiting full technical inspection by the dealership's service team; an official mechanical diagnosis remains pending. The dealership service advisor has verbally confirmed awareness of an active engine and powertrain/transmission recall affecting this vehicle. The failed component — the L87 6.2L V8 engine and associated drivetrain — is available for inspection

NHTSA ID

11724367

Incident

Mar 13, 2026

Rear Axle is grinding. Took vehicle into dealer and it is the well documented rear axle issue but this vehicle is not included in a recall. The differential fluid was replaced and figure 8s were done but there is still grinding. The rear axle also drags at times when in auto 4wd. The dealer said the next step would be to replace the axle. This is the issue: Differential Noise/Failure: Reports indicate a rubbing noise while turning, often attributed to the rear differential. In some cases, the entire rear differential has required replacement.

NHTSA ID

11722922

Incident

Jan 1, 2026

My [XXX] Daughter lost the ability to put the vehicle in reverse while running errands on a Saturday. We had to push the truck out of the parking spot "backwards" in neutral in order to get the vehicle in a position to put it in "drive". She had been going in and out of shopping centers (forwards and backwards) earlier when the reverse suddenly stopped. I dropped the vehicle at a nearby auto shop in a fit of desperation (maybe 1/2 mile away). They told me they thought the transmission was shot, so I picked it up and took it to Andean Chevrolet (Dealer) in Cumming, GA. While driving it to Andean on Tuesday (2/17), the transmission went into low acceleration mode where I couldn't go into upper gears and topped-out at 3,500 rpm's max for the 13+ miles (30 min) drive. Andean confirmed on Friday (2/19) that the entire transmission is shot with metal all inside of the fluid, gears being broken, and the valve body being broken. The truck is 5.5 years old with 93K mile on it and we were just shocked. The repair for GM Reman transmission was quoted at ~$9.2K and we just finalized a call directly with GM Customer Service to see if GM would offer any discounts to the Dealer on the repairs. We are still waiting on that result while the repairs are being made. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11719462

Incident

Feb 14, 2026

The contact owns a 2021 Chevrolet Suburban. The contact stated that while driving 45 MPH, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended, and the vehicle decelerated unintendedly. Additionally, the vehicle failed to exceed 42 MPH. Later in the day, the gear shifter was shifted to reverse; however, the vehicle failed to reverse as intended. The vehicle was taken to the dealer, where it was diagnosed with transmission valve body failure. The contact was informed that the transmission valve body needed to be replaced. The vehicle was repaired. The contact stated that the vehicle was at the dealer from December 2024 until June 2025. The vehicle was picked up from the dealer. The contact stated that while driving at an undisclosed speed, the engine seized and failed to restart. The vehicle was towed back to the dealer, where the contact was informed that the fuel pump had failed, and the battery was drained. The contact was informed that the battery and the fuel pump needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure, and a case was filed. The failure mileage was approximately 35,000.

NHTSA ID

11718829

Incident

Dec 18, 2024

Mileage

35,000 mi

The contact owns a 2021 Chevrolet Suburban. The contact stated that while in reverse (R), the vehicle failed to reverse as intended. The contact’s wife continued driving at approximately 55 MPH, and an unknown message was displayed, and the vehicle failed to exceed 55 MPH. Additionally, the transmission was stuck in gear and failed to upshift into the next gear as designed. The vehicle was pulled over to the side of the road, and the battery was disconnected and reconnected, but the message remained displayed. The vehicle was towed to an independent mechanic, where it was determined that the transmission control valve needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 81,600.

NHTSA ID

11717307

Incident

Feb 8, 2026

Mileage

81,600 mi

My vehicle will not go in reverse.

NHTSA ID

11715642

Incident

Feb 2, 2026

I have a 2021 Chevy Suburban with the L87 6.2L V8 engine. At 7k miles, we have lost propulsion, leaving the car undrivable. resulted in the dealer replacing all 16 lifters under a recognized bulletin. I never received extended 6yr 100k mile powertrain warranty as described in the bulletin. Since then, There have been 3 other issues with loss of propulsion, resulting in replacement of fuel pump modulator. belt pulley system, One of the incidents left us without power or control of our vehicle on the interstate, with no where to pull over or get out of the way of oncoming semi trucks. The last incident again left the vehicle undriveable at 84k miles, with the dealer currently reporting that it is a lifter and cam shaft issue. Resulting in a 10k bill. They state that it is not covered under the recall of these engines because it is the top of the engine versus the bottom. Clearly, the engine oil problem noted in the recall has contributed to these issues . and the crankshaft not syncing properly with the lifters.

NHTSA ID

11704228

Incident

Nov 29, 2025

Engine is skipping when in reverse.

NHTSA ID

11671818

Incident

Jun 1, 2025

The vehicle started rumbling/vibrating/shaking when getting up to speed and at a consistent speed. Brought to an independent service center and was old that the torque converter is failing. No warning lamps or other problems prior to rumbling/vibrating that started on 5/22/25.

NHTSA ID

11667883

Incident

May 22, 2025

While driving at normal highway speed, the vehicle speed is suddenly reduced and it feels and sounds like the transmission has shifted into low gear. The following warning light activated: Reduced Acceleration Drive with Care. The GM dealership service center stated that the transmission control valve body needed to be replaced. They indicated that this was a known issue. I believe a safety recall should be issued for this defective part.

NHTSA ID

11662243

Incident

Mar 10, 2025

Sat may 3rd We went for tire change from that date since that day, every time we try to start the car there’s always a different warning light The warning light is never the same issue. On may 15 when we received a warning light about transmission we went to the dealership that day they said they were about two weeks backed up but flushed the transmission and paid $504 for the service. Since that day we also received numerous warning light which include. Driver window. Esc. Winshield fluid. Tire pressure. Lift gate open. Forward Collision System Unavailable. Your 2021 Chevrolet Suburban detects a battery, starter or connection issue. Lastly the check engine light came on and the car won’t start.

NHTSA ID

11661849

Incident

May 3, 2025

History of transmission shifting issues shortly after purchase (CPO from Dealership). Vehicle was taken to two separate dealerships, several times for this issue while still under the 100,000 mile CPO warranty. Dealerships claimed they could not replicate the issue, however problem continued. Now at 1198xx miles, the transmission failed while driving. was accelerating from stop and and the vehicle bucked, the rpms jumped, the service indicator illuminated, and when the vehicle stuck in limp mode. I spoke with one of the dealerships and explained the history and suggested my vehicle failure was exactly as described in the safety recall and they informed my VIN was not included in any recall or service campaign and the could do nothing for me. I called the GM customer service number, pled my case and was told the same thing

NHTSA ID

11652215

Incident

Mar 30, 2025

After making a left turn on the street and picking up speed to 30mph the vehicle suddenly almost stopped and the engine raved up. It was so dramatic and unexpected that we thought the vehicle behind us was gonna hit us. Now vehicle only drives forward without shifting gears and doesn’t go reverse.

NHTSA ID

11651710

Incident

Mar 30, 2025

The contact owns a 2021 Chevrolet Suburban. The contact stated that while driving at various speeds, the vehicle jerked while depressing the accelerator pedal. There was no warning light illuminated. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and the contact was informed that the VIN was not covered under NHTSA Campaign Number: 24V797000 (Power Train), which the contact linked to the failure. The contact was referred to the NHTSA Hotline to report the failure. The vehicle was not repaired. The failure mileage was approximately 75,000.

NHTSA ID

11645017

Incident

Mar 24, 2024

Mileage

75,000 mi

Vehicle suddenly died and wont restart. The fuel control module was previously replaced. There was a recall for certain VINs but mine wasn't included even though I experienced the failure of the recalled part! This is extremely dangerous for the vehicle to suddenly die under way. In 2022 the fuel control module was replaced after the dangerous failure. The NHTSA recall that was for this part but excluded my vehicle is N212332040. You need to immediately include other VINs for this recall! Today I experienced the same symptoms. The car died while in gear and running and would not restart. The dealer is diagnosing the issue to determine if it is the same fuel control module. I highly suspect it is. If it isn't, there is another extremely dangerous defect with this vehicle.

NHTSA ID

11641993

Incident

Feb 11, 2025