2023 Mazda CX-5

On 09/01/2026 at approximately 55 mph, I was driving with adaptive cruise control engaged. The vehicle ahead decelerated abruptly. My vehicle began braking hard with no input from me for a fraction of a second. A red BRAKE warning appeared in the instrument cluster with an audible alarm. I then applied the brake pedal hard. On first contact the pedal barely moved from its rest position and was extremely firm. About a second into my application, while still traveling at over 25 mph, pedal resistance dropped sharply and pedal travel increased substantially. I had to push the pedal several inches farther to get back to comparable deceleration. The pedal did not pulse or vibrate. I came to a matching speed roughly one car length from the vehicle ahead, and only because I kept braking hard. I did not see an MRCC Cancelled message, though the BRAKE warning occupies the same part of the display, so I cannot say whether the initial deceleration came from Mazda Radar Cruise Control or Smart Brake Support. No brake, ABS, or DSC warning lamp illuminated before, during, or after the event, and none has since. There were no symptoms beforehand, and the brakes have worked normally since. Failed component: unknown. I cannot determine whether the change in pedal feel came from the brake booster, the DSC hydraulic control unit, the master cylinder, or the driver assistance system handing brake control back to me. The vehicle has not been inspected by anyone and no service center has reproduced the issue. The vehicle is available for inspection if needed. If a driver assistance system is commanding brake pressure and withdraws it during the driver intervention, total deceleration can drop at the moment when the driver still wants to stop aggressively to avoid a crash. Suddenly, the driver has to find the extra pedal travel while still closing on the obstacle. I slowed to a safe speed in time. With less room, or less attentiveness, I may not have been able to.

On October 16, 2025, while slowly pulling into a parking space, my vehicle experienced sudden and unintended acceleration without driver input. I did not depress the accelerator. Despite attempting to stop the vehicle, I was unable to do so. The vehicle mounted the curb, entered the sidewalk area, and struck a community mailbox, a tree, and two legally parked vehicles. My vehicle and the two parked vehicles were declared total losses. At the time of the incident, pedestrians, including toddlers, were present on the sidewalk. This loss of vehicle control created an immediate and severe risk of serious bodily injury or death. Post-incident diagnostics indicated multiple system errors, including but not limited to: •Powertrain Control Module •Anti-lock Brake System (ABS) •Instrument Cluster •Smart Brake Support / Mazda Radar Cruise Control Of particular concern is that Mazda, through its authorized dealer Rosenthal Mazda of Gaithersburg, Maryland, had prior notice of abnormal vehicle behavior. On two separate occasions before the crash, I reported that the vehicle would jolt suddenly, as if struck from behind, and at times felt as though it was attempting to accelerate without input. On each occasion, I was informed that the dealer could not duplicate the issue. No corrective action was taken, and the vehicle was returned to service. This event constitutes a serious safety failure involving unintended acceleration and apparent braking or electronic control system malfunction in this-model vehicle. Given the involvement of advanced driver assistance systems and braking components, this matter warrants immediate and thorough review.

What component or system failed or malfunctioned, and is it available for inspection upon request? - Smart Brake Support (SBS) & Forward Obstruction Warning system malfunctioned. Front radar sensor malfunctioned. Parking brake malfunctioned. I-activesense system malfunctioned. Emergency lane keep disabled. Dynamic stability control malfunctioned. Traction control system not operating correctly. Anti-lock brake system (ABS) malfunctioned. Brake system not responding. How was your safety or the safety of others put at risk? In total 10 malfunctions led to brake not responding and could not stop the car and resulted into a car accident. Has the problem been reproduced or confirmed by a dealer or independent service center? NO Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? POLICE report from car accident states brake malfunction. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? Car was totally fine until all 10 error messages appeared on Jan.17th 2026 12:42-12:43PM and immediately the brake system did not respond and resulted in the car accident. **important** Police report documented that the officer on scene is a witness of the car dashboard shows “brake malfunction”

After driving a few mile, the following two warnings come up * Smart Brake System Malfunction * Forward Radar Sensor System malfunction. If I turn off the car and then restart, the warnings go away. However, it comes back if I drive for a while again. I have visited dealership a few times for the same issue, they replaced the wheel bearing and brake switch. The warning disappeared for days and came back.

The vehicle continues to have safety features malfunctions with its sensors. The forward facing camera sensor and the Blind Spot Monitoring Sensor continues to malfunctions when driving in clear visibility with light to heavy traffic at random times during a day. These features assist the driver to maintain a safe distance from other vehicles while driving. My vehicle has almost crashed several times due to the failures of the features such as the stop and go traffic and forward facing crash detection not working properly.