Mazda 3 Owner's Manual page 287

NOTE
In the following cases, the Blind Spot Monitoring (BSM) warning indication/warning
light turns on and operation of the system is stopped. If the Blind Spot Monitoring
(BSM) warning indication/warning light remains illuminated, have the vehicle
inspected at an Authorised Mazda Dealer as soon as possible.
Some problem with the system including the Blind Spot Monitoring (BSM) warning
indicator lights has occurred.
A large deviation in the installation position of a radar sensor (rear) on the vehicle
has occurred.
There is a large accumulation of snow or ice on the rear bumper near a radar sensor
(rear).
Driving on snow-covered roads for long periods.
The temperature near the radar sensors becomes extremely hot due to driving for
long periods on slopes during the summer.
The battery voltage has decreased.
When Driving
i-ACTIVSENSE
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