Mazda 2015 5 Owner's Manual page 163

Sensor detection condition
The system can be used when the ignition is switched ON and the Park Assist Sensor
Switch has been turned on.
The system will then operate when the shift lever is placed in reverse (R).
The sensors detect obstructions under the following conditions:
Sensor
Rear Sensor The shift lever is in reverse (R).
Rear Corner Sensor The shift lever is in reverse (R), and the vehicle speed is about 10 km/h (6 mph) or less.
The system is cancelled under the following conditions:
The vehicle speed is 10 km/h (6 mph) or more.
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The parking sensor switch is pressed while the parking sensor is in operation.
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Starting and Driving
Condition
Driving Your Mazda
5-37