Defect caused by a software bug.
Mazda has filed a notice with the United States National Highway Traffic Safety Administration (NHTSA) about a safety defect identified in some Mazda3 vehicles of model year 2019 and model year 2020. A defect causes the vehicle to stop unexpectedly while driving due to the unintentional activation of the Smart Braking System (SBS).
The cause of the defect is an error in the SBS control software, due to which the system mistakenly believes that an obstacle has been detected in front of the car. To avoid a collision or to reduce damage from it, the system automatically performs braking, although there is no risk of a collision in this case. In this case, she gives a message and a warning sound signal. Obviously, if the SBS automatic emergency braking system suddenly activates while driving, there is an increased risk of a collision with a vehicle driving behind.
So far, not a single incident has been recorded when the result of the described defect would be injuries or deaths.
The problem affects approximately 35,390 Mazda3 cars sold in the USA.