2021 Mazda CX-9 Problems

The vehicle was parked stationary in the driveway with the engine running for 3-5 minutes with the A/C on. The vehicle then accelerated forward into my garage causing damage. Once I entered the vehicle, both the dash and shifter displayed park. Current TCU system internal failures have been reported from the pulling of data from Mazda.

1) What component or system failed or malfunctioned: On 6/12/2026 While drive on the highway with our daughter in the car and we experienced a high speed stall. The engine failed and we lost power. We barely got the car of the highway and coasted into a parking lot. 2) Life threating for Father, Mother and daughter and other drivers on the highway. 3) The Mazda dealer stated they were unable to reproduced problem. The diagnostic report showed few random misfired on two cylinders 2 & 3. Autozone detected codes P0300 with Secondary DTCs U0442-00 4) There car was only inspected by the dealer. The vehicle has not been inspected by Mazda the manufacturer. We requested Mazda to escalate this to the District Service Manger and to open hotline call with Mazda corporate but both of these were denied. All our service has been performed at Mazda dealer, including oil changes. We have always received a video of them working on our car with a detailed summary of what done. We did not receive the video or diagnostic report for this issue. 5) There were no warning lamps, no messages or other symptoms of the problem prior to the failure.

I entered the interstate normally, with no issues accelerating or merging. While driving at approximately 70 mph, in traffic, all three warning messages appeared on the instrument cluster at the same time: “Smart Brake System Malfunction,” “Driver Attention Alert System Malfunction,” and “Forward Smart City Brake Support Malfunction.” At the same moment, the vehicle began to lose speed. I pressed the accelerator pedal firmly. The speed continued to decrease instead of increasing. I could not accelerate at all. An exit was thankfully immediately available. I took the exit, then continued on a side road, then into a parking lot before I could find a safe place to stop. At no point did the pedal work again — I was immensely lucky to navigate safely, especially with my toddler in back seat. Other traffic was present on the interstate at the time. The sudden loss of throttle at that speed, with traffic present on each road and merging across numerous lanes in [XXX] traffic, created a serious risk of collision while I searched for a safe stop. The vehicle has not been inspected by a dealer, it’s with Hiley Mazda of Hurst dealership in [XXX] now. TBD whether the problem can be reproduced. The vehicle can be available for inspection if needed. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The vehicle was parked stationary in the driveway with the engine running for 3-5 minutes with the A/C on. The vehicle then accelerated forward into my garage causing damage. Once I entered the vehicle, both the dash and shifter displayed park. Current TCU system internal failures have been reported from the pulling of data from Mazda.

I entered the interstate normally, with no issues accelerating or merging. While driving at approximately 70 mph, in traffic, all three warning messages appeared on the instrument cluster at the same time: “Smart Brake System Malfunction,” “Driver Attention Alert System Malfunction,” and “Forward Smart City Brake Support Malfunction.” At the same moment, the vehicle began to lose speed. I pressed the accelerator pedal firmly. The speed continued to decrease instead of increasing. I could not accelerate at all. An exit was thankfully immediately available. I took the exit, then continued on a side road, then into a parking lot before I could find a safe place to stop. At no point did the pedal work again — I was immensely lucky to navigate safely, especially with my toddler in back seat. Other traffic was present on the interstate at the time. The sudden loss of throttle at that speed, with traffic present on each road and merging across numerous lanes in [XXX] traffic, created a serious risk of collision while I searched for a safe stop. The vehicle has not been inspected by a dealer, it’s with Hiley Mazda of Hurst dealership in [XXX] now. TBD whether the problem can be reproduced. The vehicle can be available for inspection if needed. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The vehicle was parked stationary in the driveway with the engine running for 3-5 minutes with the A/C on. The vehicle then accelerated forward into my garage causing damage. Once I entered the vehicle, both the dash and shifter displayed park. Current TCU system internal failures have been reported from the pulling of data from Mazda.

Hello, I have been to a Mazda dealer complaining of clicking and squeaky brakes for 2 years now. Dealer replaced both front and back breaks and rotors around 22k year ago and to my surprise the issues persist, currently vehicle is at 49k. There is a TSB( 04-001/22) out for my vin and year, so they know its a manufacturing defect and all they do is throw white break grease and a month later the noise is there again when breaking , backing up. I am not the only one, people of reddit confirm this and so does a general google search. Besides that i love the car and the dealer was super cool about it all but I'm sorry, this is unacceptable, Every time i go get an oil change i ask about a fix and nothing.

6/29/2023--Vehicle stopped suddenly with i-ACTIVESENSE system malfunction, Dynamic Stability Control malfunction, Engine malfunction, engine output reduced, Front radar sensor malfunction. Dealer said these faults due to bad battery--replaced battery per Service Manager [XXX] at Lakeland Mazda. 9/10/2023--Incident #2 with same faults as above with vehicle stopping suddenly at risk of creating a rear end collision. Lakeland Service Manager [XXX] now said that the faults are due to a faulty ERG valve. Lakeland Mazda and [XXX] are absolutely clueless as to the root cause of this problem and are releasing the vehicle back to the customer with the potential of causing a significant collision that can result in serious injury and/or death. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

2021 Mazda CX-9 Frontal collision at a speed between 10-20 mph. Car shut down after collision and was not drivable. Concern is the driver side airbag did not deploy. (Neither did passenger but there was no person in the passenger seat)

REAR PASSENGER HANDLE AND HOOK ABOVE SEAT IN ROOF SPLINTERED INTO SHARP PROJECTILES FLYING THROUGH CABIN WHEN AIR BAG DEPLOPYED I SHOWED THE SHARP PIECES TO MY INSURANCE ADJUSTER THE POWER OF THE RIGHT CURTAIN AIR BAG DEPLOYMENT BROKE THE HANDLE TO PIECES AND IF ANYONE HAD BEEN IN THE BACK SEAT THEY COULD HAVE HAD AN EYE PUT OUT OR BEEN EMPLAILED BY THE SHARP PIECES

On a high-speed highway (Route 14), the vehicle suffered a sudden flat tire/air loss event, forcing an emergency pull-off onto a narrow shoulder with 65 mph traffic. Subsequent inspection revealed the failed tire and the rest of the set were manufactured in late 2007 (DOT code 4907). These 19-year-old tires were installed by a professional tire shop despite being far beyond their safe service life. Component/System Failed: Tires (Set of 4). Tire Size: 255/50 R20 (Vredestein Wintrac 4 Xtreme, DOT 4907). Available for inspection upon request. Safety Risk: Sudden tire failure at highway speeds created immediate loss-of-control risks and exposed occupants to high-speed semi-truck traffic on a narrow shoulder. Confirmation/Inspection: DOT date code 4907 confirmed by visual inspection. The installing tire shop was notified and acknowledged the sale/installation. Not yet inspected by manufacturer or law enforcement. Warning Signs: No warning lights, pressure drops, or symptoms occurred prior to failure. UNKNOWN if internal tread separation preceded deflation.

On 4/30/2022 the rear door lift gate opened unexpectedly and hit the ceiling of a parking garage (The Summit at Las Calinas, Irving Texas) , the glass window shattered, glass fell in and outside the car. An unfamiliar beeping was heard before the accident, but the source could not be located prior to the impact with the ceiling. A lift gate ajar warning indicator light likely flashed on the dash but was not noticed. We surmised that the root cause was likely due to unintentional pressing of the rear lift gate key fob button (driver had put key fob in pants pocket). This unintentional and unexpected opening of the lift gate has happened on at least 4 prior occasions when the key fob lift gate button has been unintentional pressed. One time resulting in being hit in the head with the lift gate! Potential Risks: 1) People near the rear of the car can be struck when the lift gate unexpectedly opens, 2) Young children who are sitting in the third seat are exposed, 3) Trunk contents can spill out if not secured, 4) Valuables are exposed if lift gate opens while parked unbeknownst to the driver, 5) Damage to vehicle if rear lift gate opens in a home garage and hits the garage door, 6) other Mazda owners as reported on Reddit.(https://www.reddit.com/r/MazdaCX9/comments/mf3h5w/back_trunk_opening_by_itself/) Problem was reported to TOWN NORTH MAZDA dealer. Insurance claim not filed because cost of window replacement is below deductible. We were grateful that no one was hurt and that the car could be driven home.

The oil light keeps coming on before your initial oil change. Also, the oil is actually low. They have already changed it and I'm having the same problem in less than 2 months.

I was driving approximately 75-80 mph (speed limit for I-90 is 80 mph) on I-90 Eastbound in South Dakota (approximately 5-8 miles from Sioux Falls, SD) in the left-hand lane (passing lane with a minimal shoulder) when I heard a terrible noise that sounded like I had a flat tire and the car began to pull to the left. I immediately slowed down and steered the vehicle onto the small shoulder on the left-hand side of the interstate. It was at this point I looked out my window (driver's window) and saw the entire left front wheel (not just the rubber tire) rolling by (west in the grassy median of I-90). The vehicle did not roll over, hit another vehicle, or get hit by another vehicle. After coming to a safe stop, I got out of the vehicle and saw that the left front (driver's side) wheel (not just the rubber tire) was gone. There were two (2) other passengers in the vehicle at the time that the wheel fell off who exited the vehicle out of danger of passing cars/trucks/semi tractor trailers on I-90. The vehicle was towed and to my knowledge has not been inspected by the manufacturer. The Hertz rental vehicle was only "inspected" by PurCo claims specialist via pictures as they did not have the vehicle in their possession. There were no warning messages, lamps, lights, or other symptoms prior to the wheel falling off. The wheel fell off on 7/8/2023 on Interstate 90 in South Dakota. After the wheel fell off, it rolled down the median of I-90 bounced up onto the westbound lane of I-90 and struck another vehicle causing that vehicle's airbags to deploy. There were four (4) occupants in that vehicle.

AS I WAS DRIVING DOWNHILL WITH MINIMAL SNOW ON THE GROUND, I TAPPED MY BRAKES ABOUT 7 TIMES BEFORE THEY LOCKED UP. I WENT TO TURN TO STAY ON THE ROAD AND THE STEERING WHEEL WOULDN'T BUDGE CAUSING ME TO GO OFF THE ROAD, INTO AN EMBANKMENT. VEHICLE WAS GOING ABOUT 5-10MPH WHEN THIS OCCURED ON A CITY STREET.

The contact owns a 2021 Mazda CX-9. The contact stated while driving at various speeds and turning, there was a popping sound coming from the front end of the vehicle. The front-end popping sound also occurred while driving over bumps in the roadway. The vehicle was taken to an independent mechanic who was unable to determine the cause of the failure. The vehicle was not repaired. The local dealer and manufacturer were not notified of the failure. The failure mileage was 68,811.