2021 Chevrolet Tahoe Powertrain (other) Problems

-On the date of Monday XXX at approximately 4:30 pm est I was traveling on [XXX] and transmission felt like a possible slip happened in transmission. At approximatively 4:45pm est I made it home tried to back vehicle into parking space and reverse was lost. Vehicle didn't and wouldn't shift into reverse. I had to push vehicle in spot backwards. No check engine or warning lights were displayed on dash. - On Tuesday XXX. I contacted [XXX] of [XXX] approximately at 8:30 am est. [XXX] answered. I explained the symptoms and asked If I could bring in within the hour or so. He stated it would be fine to bring in. - At approximately 9:10 am est My girlfriend and [XXX] daughter got in vehicle. Started vehicle no service lights were on, but had no reverse still no reverse. My girlfriends mother was following us to pick us up at dealership as we dont have a 2nd vehicle. We started out driveway to [XXX]. I had no problems at 1st then prior to the intersection of [XXX] the Vehicle lost control on its own. The sequences happened fast and abrupt. 1. Vehicle downshifted roughly to about 3 gear 2. Lost power steering 3. engine over revved 4. vehicle pulled right. During this time as a professional trained driver. I removed us off [XXX] off road way on to [XXX] (To the right) to avoid being in an accident. I would say that the speed was roughly 20MPH at turn as I was avoiding the accident that could of potentially happened. I was not on asphalt the whole time to make turn as I had a limited vehicle (Not properly functional). I was able to stop at [XXX] to stop. Stopped on Brigantine is when I pointed out to my girlfriend that the lights just came on. in the meantime, we received a phone call from [XXX] (Girlfriends mom) asking where we went as she didn't see us. We explained to her situation, and she met on Brigantine and followed us to dealership. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11754265

Incident

Jun 23, 2026

I purchased my vehicle new in 2020. It presently has around 83,000 miles. From early on, it has occasionally hesitated, then jumped when putting the car in reverse. I spoke to the dealership years ago but they said it was nothing. On July 19, 2026, my car randomly would not shift above (probably) second gear on the highway. After parking, it would not shift into reverse at all. The vehicle was towed more than 30 miles to my hometown dealership as it was inoperable. It now requires something approaching a transmission replacement costing between $2500-4500, or more. I am aware that this is a recurring problem with GM vehicles of this type and era, and it seems absurd to have so many vehicles with failing transmissions before they even reach 100,000 miles.

NHTSA ID

11753041

Incident

Jul 19, 2026

My transmission failed and it has been in a shop for 2 months. The pistons in the transmission failed not sure why but made it not go in reverse. The parts were on backorder for atleast a month. The warranty is out and my extended warranty will not pay because Chevorlet Dealership failed to flush my transmission when it was in for service. The transmission is a known problem on these models and was recalled for the diesel models but not the gas models.

NHTSA ID

11748993

Incident

Jun 2, 2026

DATE: 06/17/2026 The engine shuts off without warning while I am driving, recurring roughly every 10 miles. When it stalls, the dashboard and electrical accessories stay on, but the vehicle loses motive power, along with power steering assist and power brake assist, which is extremely dangerous at road speed and in traffic. This began immediately after dealer service completed on 6/18/2026. During that visit the dealer performed two safety recalls (N252494000, the "L87 Engine Loss of Propulsion" PicoScope inspection with oil change; and N252510321, ECM software reprogramming) and a valve lifter replacement that required removing both cylinder heads. The vehicle was running and fully drivable when I dropped it off, and was returned stalling repeatedly while driving. It never did this before the service. At first the engine would not restart after stalling. The dealer replaced the starter; it now restarts but continues to stall every ~10 miles. A dealer diagnostic scan recorded numerous "Lost Communication" codes across nearly all control modules, plus control-module input-power codes showing low voltage and power-circuit correlation faults (e.g., U3505, U3018, U3007) and an active loss-of-communication code for the power steering module — consistent with an intermittent loss of electrical power or ground affecting engine control. The engine passed the recall's connecting-rod/crankshaft (PicoScope) inspection, so this is not the recalled bearing failure mode. The vehicle is currently at the dealership and is undrivable. The dealer has ordered a new engine and apparently also a new radiator for reasons unknown. No crash or injury has occurred to date, but the vehicle lost power while on the freeway at speed multiple times. A GM customer assistance case is open. Repair orders and the diagnostic scan are available on request.

NHTSA ID

11747941

Incident

Jun 18, 2026

The engine's Dynamic Fuel Management (DFM) lifter failed and damaged the camshaft at around 70,700 miles. The broken components are available for inspection upon request. This failure put occupants at risk because the vehicle suddenly lost power, began shaking violently, and could not accelerate safely in traffic. This unexpected loss of propulsion created an immediate collision hazard. The problem was officially diagnosed and confirmed by a repair service center. It has not been inspected by police or insurance representatives. There were no advance warning signs. At the exact moment of the failure, the check engine light started flashing, the car began shaking heavily, and the engine made a loud knocking sound.

NHTSA ID

11747364

Incident

Jun 15, 2026

We have a 2021 Chevy. Tahoe, and we just had an inspection done because a light kept coming on saying that our engine might fail. The shop initially said it needed cam shaft replacement, but now are saying the entire engine needs to be replaced. The care has ~ 67,000 miles on it and is 5 years old.

NHTSA ID

11746218

Incident

Apr 10, 2026

Rear end makes noise when turning, been flushed based on current bulletin. Still makes noise but not as bad. Now transmission is jerking at multiple gears

NHTSA ID

11745295

Incident

Apr 1, 2026

My vehicle would not shift into reverse. Took it into the Chevrolet service and they said the Valve body needs replaced. There are known issues with the Valve body in 2021 Tahoe but they said it is not covered under any of the GM extended warranties. It should be covered under Special Coverage N242454441 or N242454440, but they said no coverage. The vehicle only has 46,200 miles on it

NHTSA ID

11743568

Incident

Jun 9, 2026

Transmission failed. Only warning was check engine light on 10 minutes prior to failure. At 30 mph on city road car was suddenly coasting, engine rpms revved to 7-8k, no driving power available for approximately 30 seconds. 'Drive' reingaged but apparently in limp mode enough to get a few hundred yards more to parking lot. No reverse gear available and warning on dash 'catastrophic failure' imminent. Garage reports the transmission is 'bad' . Awaiting dealership input but 3 weeks before they will look at it .

NHTSA ID

11739913

Incident

May 21, 2026

The contact owns a . The contact stated that while driving in reverse a loud popping noise had occurred coming from the engine compartment. Later, while driving up a hill was warning message "Accelerator, Reduced Speed" had displayed and the vehicle was slowly driven home. The contact later discovered that the vehicle also did not operate in reverse. The vehicle was taken to the local mechanic who diagnosed that the transmission valve body was faulty and needed to be replaced. The vehicle was not yet repaired. The local dealer and manufacturer were notified of the failure but no assistance was offered.. The failure mileage was 85,000.

NHTSA ID

11735997

Incident

Mar 23, 2026

Mileage

85,000 mi

My Tahoe has 108,000 miles on it. It broke down in the middle of the road and refused to go into gear with zero symptoms prior to this. We had it towed to the dealership and were told it is the Transmission Valve Body. This is a known issue but our VIN isn't covered for some reason so we have to pay out of pocket for this costly repair that is a known problem!

NHTSA ID

11731354

Incident

Apr 3, 2026

The component at issue is the engine, which suffered a sudden and catastrophic failure due to unknown causes. At no time prior to this incident were there any warnings, symptoms, or indications of an underlying mechanical defect that would have allowed for preventative action. While operating the vehicle on the highway with my family present, multiple warning indicators activated simultaneously, including a blinking check engine light, traction control light, ESC warning, and a forward collision warning. Immediately thereafter, the vehicle experienced a rapid and significant loss of power accompanied by a loud and persistent engine knocking noise, rendering the vehicle unsafe to operate and placing the occupants at risk. It is important to emphasize that traction control and ESC systems are not causally related to an engine misfire condition, further supporting that this event was abrupt and not part of a progressive or diagnosable issue. A diagnostic scan performed at that time identified a misfire in cylinder 1. Upon delivery of the vehicle to the dealership for inspection, it was determined that the engine had suffered complete internal failure and was deemed “blown.” This finding confirms the occurrence of a catastrophic mechanical breakdown. Based on the sudden onset, absence of prior warning, and severity of the failure, there is no reasonable basis to attribute this condition to normal wear and tear, operator misuse, or neglect. Rather, the facts support the conclusion that this was the result of a latent defect or internal mechanical failure beyond the operator’s control. Accordingly, this matter should be addressed under applicable warranty coverage or consumer protection standards.

NHTSA ID

11730632

Incident

Apr 5, 2026

Driving down the highway and I lost all the gears it went from driving speed then wouldn’t go over 30 mph. When I got pulled into a business on the side of the road then tried to restart it it then wouldn’t go into reverse. It was dangerous because there was cars behind me going the speed limit then my car just lost speed. No warnings it’s not throwing any codes. Looking on the internet it seems it’s the transmission or valve body

NHTSA ID

11723103

Incident

Feb 27, 2026

I was driving yesterday and noticed my transmission started to shift hard and unnecessarily. Then I received a warning that propulsion was affected and to drive with care. The check engine light came on. I was able to make it home, but the vehicle wouldn't go into reverse. I had it towed to a dealership today and they identified the issue as being related to the valve body. Apparently a recall was just issued for this on the 2022 Chevy Tahoes. I'm not sure why this isn't being extended to the 2021 model.

NHTSA ID

11721561

Incident

Mar 1, 2026

The contact owns a 2021 Chevrolet Tahoe. The contact stated that while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The vehicle lost motive power, and the transmission slammed into gear, and it felt like the vehicle was rear-ended. No warning lights were illuminated. 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 contact was later informed that the transmission needed to be replaced. The vehicle was being repaired. The contact stated that the failure was a known failure with the vehicle. The manufacturer was made aware of the failure, and a case was filed. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 62,000.

NHTSA ID

11721469

Incident

Feb 24, 2026

Mileage

62,000 mi

Transmission issue -while driving 55 mph the RPM’s revved up and the vehicle felt as it it was in 2nd or 3rd gear. Warning lights came on stating “rapid deceleration use caution” and the engine light came on. The vehicle was able to go into park but upon shifting back into drive, it did not change gears. Sounds as if it is being driven in 2nd or 3rd gear with RPM’s elevated.

NHTSA ID

11721408

Incident

Feb 28, 2026

#1 ) el motor presento esta fallas en las 98mil millas, el motor empezó con un alto consumo de aceite de 5 cuartos de aceite cada 3 mil millas, en repetidas ocasiones estábamos de viaje junto a mi familia, mi esposa, [XXX]. Un dia Hicimos una para frente a un semáforo, y en seguida el vehículo empezo a tirar una gran cantidad de humo blanco por la salida de los escapes, mis hijas entraron en pánico una de ellas intento salir del vehículo en plena calle principal, ella sintió miedo y pensó que el vehículo se estaba incendiando. En ese momento le dije que es un problema de el vehículo pero que no era incendio. El humo que sale repentinamente es derivado de el excesivo consumo de de aceite en el motor. A mi punto de vista esto representa un alto riesgo en la carretera. Poniendo riesgo la vida de mi familia, la mía misma y la terceros en la carretera. El aceite que consume significa que esta llegando a las cámaras de combustión en el motor y esto puede deribar, que en un momento determinado el aceite sirva como combustible y el vehículo en marcha se acelere sin control y provocar graves danos a la integridad de mi familia y asta la muerte de terceras personasla carretera. #2) la transmisión en este vehículo tironea bruscamente cuando hace un cambio de velocidad esto representa un alto riesgo para mi familia, este vehículo representa un alto riesgo de que cuando haga un cambio de marcha rompa algunos componentes internos y esto lleve a una parada repentina y provocar un accidente mortal. #3) últimamente este vehículo a presentado inestabilidad en el volante, a la fecha de esta nota el problema tiene al rededor 5 días . El vehículo se llevo al consecionario Maik Chevrolet ubicado en 11711 Katy fresa y, houston tx 77079, ellos hicieron las respectivas pruebas en el vehículo y determinaron que el vehículo no era apto para estar en la carrtera debido a las fallas que presenta en la transmisión y el motor. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11721272

Incident

Oct 22, 2025

While driving my 2021 Chevrolet Tahoe at highway speeds (approximately 60 mph), the transmission suddenly malfunctioned due to what the dealership is telling was a valve body failure. Without warning, the vehicle lost proper propulsion and began to decelerate rapidly in active traffic. I did not receive adequate warning before the failure occurred. The sudden loss of power at highway speed created a very dangerous situation. Vehicles behind me had to brake abruptly, and I was nearly rear-ended. This presented a serious safety risk to me, my three children, and surrounding drivers. The issue was later diagnosed as a transmission valve body failure. A failure of this nature should not occur on a relatively new vehicle, and there Is currently a recall on other 2021 Tahoe’s for this same issues. My car is sitting at the Chevy dealership waiting for a full valve body replacement, which the dealership said they are having issues getting the part and will take over 2 weeks. The cost is around 5k to fix.

NHTSA ID

11721164

Incident

Feb 22, 2026

The contact owns a 2021 Chevrolet Tahoe. The contact stated that while driving and attempting to slow down to approximately 35 MPH, there was an abnormal clunking sound coming from the vehicle. The contact believed that the sound was caused by ice buildup on the mud flap, but shortly afterwards, the engine revved unexpectedly, with the check engine warning light illuminated, and the message “Reduce Acceleration - Drive with Care” was displayed. The vehicle started to coast unintendedly. The contact stated the vehicle returned to normal operation after a short while. The vehicle was taken to a local dealer to be diagnosed. The mechanics pushed the vehicle out of the parking spot before inspecting the vehicle. The vehicle was diagnosed with transmission valve body failure. The contact was informed that the transmission valve body needed to be replaced. The vehicle was not repaired. The manufacturer was contacted and referred the contact to the NHTSA Hotline to report the failure. The approximate failure mileage was 88,342

NHTSA ID

11717741

Incident

Feb 4, 2026

Mileage

88,342 mi

2021 tahoe with 3.0L diesel engine and 139k miles recently began overheating when on interstate but temp would jump up quickly then quickly back down. Reduced acceleration mode is triggered and AC is turned off automatically. Diagnostic report shows coolant control valve error code and it was explained to me that valve is sticking then as engine pressure rises, it knocks it loose again explaining the quickly jumps and dips in temp. Fan runs constantly from moment it is started too. When looking for the part online to get an idea of repair cost, there was a bulletin about this being a known issue in the 2021 tahoes with the diesel engines and bulletin states GM extended special coverage for 15yrs/150k miles. When I called dealer to schedule service, I was told this bulletin doesnt come up under my vin number despite it having the same issues, error codes, year, make, model, and engine.

NHTSA ID

11716126

Incident

Jan 12, 2026

The contact owns a 2021 Chevrolet Tahoe. The contact stated that while driving at an undisclosed speed, there was a loud grinding sound coming from the rear of the vehicle. There was no warning light illuminated. The vehicle was taken to the dealer and was diagnosed with failure. The contact was informed that the rear differential assembly needed to be replaced. The vehicle was not repaired. The contact related the failure with NHTSA Campaign Number: 22V036000 (Power Train); however, the VIN was not included. The manufacturer was made aware of the failure. The approximate failure mileage was 95,000.

NHTSA ID

11715576

Incident

Feb 4, 2026

Mileage

95,000 mi

6.2l motor blew up set at dealership for 4 months no motor to fix it. finally got it back with in 10 days the torque converter need replaced in the transmission. out of service out f service for motor june 19 2025 got it back october 20 2025. transmission went out 10mdays later

NHTSA ID

11711932

Incident

Jun 19, 2025

* Sudden Catastrophic Engine Failure. * The car lost power in the middle of a high traffic, very dark country road, forcing her to stay in the middle of the (undivided) road in the dark hoping cars didn't slam into her. A Collin County Sheriff was dispatched to keep her safe until the tow truck arrived almost two hours later." * The vehicle was towed to a dealer where they confirmed that the torque converter, valves, lifters had failed. Dealer didn't disclose that there was any issues for these engines, which there is. It's a 6.2L V8 Tahoe High Country. * It has only been inspected by the dealer, not the manufacturer, police, insurance representatives, etc... * The vehicle indicated a traction control problem, then the engine light came on, and then the engine failed followed by loss of power. All happened in rapid succession WITH NO OPPORTUNITY FOR THE DRIVER TO GET TO A SAFE LOCATION. * There was no warning or other symptoms preceding this. The vehicle has always been faithfully serviced at Chevy dealerships consistent with the manufacturers recommendations.

NHTSA ID

11711054

Incident

Jan 13, 2026

AFM lifter collapse on Cylinder 6 Written repair estimate or a Diagnostic report showing P0306 + lifter failure

NHTSA ID

11709326

Incident

Dec 22, 2025

This vehicle has experienced multiple substantial defects, several of which directly endangered my family, including an infant, and rendered the vehicle unsafe and inoperable for extended periods despite warranty repairs. Summary of defects and failures: 1.Electronic door locking failure The vehicle experienced an electronic malfunction that caused the doors to randomly lock, resulting in my infant being locked inside the vehicle when we exited. This wiring defect was later repaired under warranty but represents a serious safety failure. 2.Fuel pump recall and highway breakdown While driving my family of six on a major highway over an hour from home, the recalled fuel pump failed while in motion, leaving us stranded on the side of the highway. We were forced to arrange an Uber for transportation. This incident placed my family in a dangerous situation and constitutes a major safety-related defect. 3.Transmission failure and extended inoperability The vehicle suffered a transmission failure that rendered it unsafe and inoperable. The dealership required over one week to schedule service and more than two additional weeks before the vehicle was inspected and repaired. The vehicle was out of safe driving condition for approximately one month. Upon return, the vehicle experienced additional failures, including a dead battery. 4.Known poor design defect – rear entertainment screens The rear entertainment system screens cracked due to a widely known poor design and placement issue, unrelated to misuse. 5.Rear headrest internal mechanism failure The internal mechanism of a rear headrest failed and requires replacement, further demonstrating ongoing quality and safety concerns. Due to the number, severity, and safety-related nature of these defects—combined with cumulative downtime exceeding 30 days—I have lost all confidence in this vehicle. I no longer consider it safe or reliable for transporting my family.

NHTSA ID

11708548

Incident

Sep 17, 2021