2021 GMC Yukon brakes problems

Filed Oct 20, 2026 · Brakes · CO

Our 2021 GMC Yukon Denali has repeatedly experienced sudden, violent braking and apparent rear-wheel lockup without the driver applying the brakes. These incidents occur without warning at highway speeds, moderate speeds, and in traffic. The vehicle abruptly decelerates, fishtails, loses stability, and produces smoke. The wheels have locked severely enough to leave skid marks on the roadway. This creates an immediate risk of losing control or being struck by another vehicle. We took the Yukon to Alpine Buick GMC on October 12, 2026. After eight days, the dealership reported that it could not reproduce the malfunction. However, its written findings confirm that an engineering case was opened and GM engineering recommended replacing the transmission valve body based on data collected from other vehicles with related concerns. The dealership proposed approximately $3,300 in repairs without providing diagnostic evidence establishing that the valve body was definitively responsible or that replacement would resolve the dangerous condition. We declined the repair and paid $229 for diagnostics. GM recalls 24V797 and 26V085 address transmission valve failures capable of causing unexpected rear-wheel lockup. Although our gasoline-powered Yukon is excluded from these recall populations, it is exhibiting similar dangerous behavior, and GM engineering has recommended replacement of the same type of component. Exclusion from a recall based on VIN does not establish that a vehicle is free from a similar safety defect. We request that the federal safety agency investigate whether this failure extends to 2021 gasoline-powered Yukons and other GM vehicles outside existing recall populations. This is a recurring, unpredictable loss-of-control hazard that could result in a serious or fatal collision. It has come very close on E470 in the center lane at 75 mph with cars in all positions around us. Do you want YOUR family in one of the cars around us?

Filed Aug 18, 2026 · Brakes, Electrical · TX

As I was driving, the vehicle's air conditioning suddenly began blowing warm/hot air. Moments later, the check engine light and all electronic service stability lights illuminated on the dashboard. Simultaneously, the vehicle suffered a complete loss of electronic brake assist, resulting in an extremely hard brake pedal and a severe reduction in braking power. The vehicle also displayed a "No Drive Mode Available" message. Third-party diagnostic scanning revealed network power codes U3018, U3505, P00FF, and P0700, indicating a total loss of power to the Body Control Module (BCM). This is the second life-threatening incident with this vehicle I have experienced following a previous highway engine stall due to engine recall. The vehicle was towed to a GM dealership for diagnostic and emergency electrical repairs.

Filed Aug 11, 2026 · Acceleration, Brakes · TX

On July 28, 2026, while traveling on vacation with my family, our vehicle experienced a catastrophic engine failure. There were warning lights displayed for 30 seconds prior to the engine failure. On July 23, 2026, one day before taking the vehicle to the dealership, the following warning indicators appeared on the dashboard and then disappeared: “Service ESC,” “Service Traction Control,” and a flashing engine light. We took the vehicle to the dealership on July 24, 2026, because we wanted to be proactive and ensure that the vehicle was safe to operate. The dealership inspected the vehicle but reported that no diagnostic trouble codes were identified and no issue was found. We picked the vehicle up from the dealership on the evening of July 27, 2026. On July 28, 2026, while traveling on the highway approximately 2.5 hours from home, the same warning messages appeared on the dashboard again. Because we were traveling at highway speeds and vehicle speed management was becoming an issue, I immediately exited the highway and stopped in a parking area. I placed the vehicle in park, at which point the engine began idling extremely rough. I could feel the vehicle shaking while sitting in the driver's seat. I exited the vehicle to open the hood, but before I was able to do so, I noticed gray smoke coming from the exhaust. We located a GMC dealership approximately two miles away. Because of the vehicle's condition, we drove there slowly on the frontage road at approximately 15 mph and dropped the vehicle off for diagnostic inspection. The GMC dealership subsequently diagnosed the vehicle with catastrophic engine failure and recommended that the engine be replaced. The vehicle remains at the dealership and is available for inspection.We made a reasonable effort to have the vehicle inspected before our trip because we were concerned about the warning indicators and wanted to ensure that the vehicle was safe to travel.

Filed Nov 6, 2025 · Brakes, Electrical · 95,000 miles · TX

The contact owns a 2021 GMC Yukon. The contact stated while driving at an undisclosed speed, the engine seized. The brake pad sensor warning light illuminated. In addition, the contact stated that the vehicle continued to roll forward. The contact was able to drive the vehicle to the shoulder of the road. The contact stated while attempting to restart the vehicle, the vehicle failed to start. The contact stated that a nearby driver assisted by providing a jumpstart. The vehicle was driven to the residence. The vehicle was then taken to an independent mechanic where it was diagnosed with alternator failure. The contact stated that the vehicle was previously taken to two independent mechanics, and the vehicle was diagnosed with alternator failure. The dealer was made aware of the failure. The contact was informed that the failure was a known failure with similar vehicles. The manufacturer was made aware of the failure with the alternator and the brake pad sensor. The contact was informed that the repairs were not covered under warranty or recall. The failure mileage was approximately 95,000.

Filed Mar 10, 2025 · Brakes, Driver assistance · NC

The component that failed was the Camshaft and Lifters in the Engine - My safety and others was put at risk because while going 45mph, I suddenly lost forward moving power and couldn't go faster than 35 - braking power was sketchy and only responsive when pumped. - I received the following errors on my dash "Service ESC" "Service Traction Control", Reduced Acceleration Drive with Care", "Forward Collision System Unavailable", "Service Emission System" the vehicle would shudder violently- this problem has been confirmed and corrected at a huge expense (see bill) -

Filed May 3, 2024 · Airbags, Brakes · MI · crash

The contact owns a 2021 GMC Yukon. The contact stated that while driving at an undisclosed speed and completing a turn, the forward warning collision system alarm sounded, but the vehicle failed to activate automatic emergency braking. As a result, the vehicle collided with another vehicle ahead. The air bags did not deploy. No warning lights were illuminated. The vehicle was taken to an independent mechanic, who diagnosed a failure with the ABS. The vehicle was not repaired. A police report was not filed, and no injuries were reported. The manufacturer was not notified of the failure. The failure mileage was unknown.

Filed Sep 21, 2023 · Brakes, Engine · MT

This GMC Yukon underwent an over the air update in remote Wyoming and was almost undriveable due to steering problems and brake malfunction. Also engine and transmission problems. It has been awaiting repair, but I have been informed that no fix is available because of transmission defect. No parts available We were nearly stranded.

Filed Jun 14, 2023 · Brakes, Electrical · 60,000 miles · MI

The contact owns a 2021 GMC Yukon. The contact stated that while driving at an undisclosed speed, the odometer was inoperable. There was an abnormal odor of fuel while starting the vehicle. The parking brake and TPMS warning lights were illuminated and flashing. The parking brake was inoperable. Additionally, the seat belts were inoperable. The contact stated that there was a cut in brake line. The vehicle was taken to the local dealer where it was diagnosed and determined that the brake master cylinder needed to be replaced. The vehicle was repaired but the failure persisted. The manufacturer was contacted but provided no additional assistance. The failure mileage was approximately 60,000.

Filed Oct 29, 2022 · Brakes, Electrical · MI

I own a 2021 GMC Yukon Denali that had TOTAL BRAKE FALIURE last Tuesday. I had it towed to a local GMC dealer and are repairing it under warranty. I was lucky to be on a back road when my brakes went out. I had no warning lights come on prior to hitting the brake pedal and was able to coast to a stop on the shoulder When I applied the brakes, the pedal went to the floor and did nothing. You can't stop the car with the parking brake because it is electric. My concern is what if I was on a busy road when this happened or what if this happens to a family in traffic they could be seriously hurt or worse yet killed. I do have good photos of my instrument panel with all of the warning lights coming on after I tried to stop. In good conscience feel that I have to at least try and report this to GM, the state and anyone else that will listen. If nothing comes of this at least I tried and just hope no one gets hurt if this happens again. My wife refuses to ride in that vehicle until I have solid answers. The dealer said they will have my car repaired this week and are replacing the master cylinder and ECS This is fine but why did it happen and how can I be sure it won't happen again? I believe in GM and have a 2023 Yukon Denali on order. I would hope that after 3 years of this model they have most of the little quirks worked out. A rep from GM did contact me and at first was talking about buying my car back but changed that today. My case number is 9-8497380349 . The problem is I have no idea when my new car is coming in our should I just cancel it and find something else. In my opinion this is a very serious problem.

Filed Oct 25, 2021 · Brakes · CA

On Friday October 22, 2021 around 7:20am as I was driving my children to school I was driving around 40 mph when suddenly I received an alert on the dashboard saying “brake system fail”, I then proceeded to brake to make sure my breaks were working when I noticed they did not work. I then started pumping the gas pedal repeatedly to make the vehicle stop. My car was not stopping and my children and I panicked and started crying. As I was getting closer to a vehicle and ready to crash I swerved the vehicle to the right where it was just an empty lot. I continue to press and pump the brakes until the vehicle came to a complete stop. I took pictures of the dash board once the vehicle was completely off. My Vehicle was towed to my house shortly after. I refuse to drive that vehicle after the terrible experience that jeopardize the life of my children and myself. We have suffered emotional distress.