Mazda CX-9 2021 Manual page 411

The ultrasonic sensors (rear) function by emitting ultrasonic waves which are reflected off
obstructions at the rear and the returning ultrasonic waves are picked up by the ultrasonic
sensors (rear).
The ultrasonic sensors (rear) are mounted in the rear bumper.
Ultrasonic Sensor (Rear)
Ultrasonic sensor (rear)
When Driving
i-ACTIVSENSE
*
*Some models.
4-245