If there is the possibility of a collision with a vehicle ahead, the beep sounds continuously and a warning is indicated in the multi-information display and the active driving display.

Smart Brake Support (SBS) (Some models)
Stopping The Smart Brake Support (SBS) System OperationMazda 6 Owners Manual: Transmitter
NOTE
(With theft-deterrent system) The hazard warning lights flash
when the theft-deterrent system is armed or turned off. Refer to Theft-Deterrent
System.
(With the advanced keyless function) A beep sound can be heard
for confirmation when the doors are locked/ unlocked using the k ...
Mazda 6 Owners Manual: Installation of radio system
If a radio system is installed improperly or if a high-powered type is used,
the CIS and other systems may be affected. When the vehicle is to be equipped
with a radio, observe the following precautions:
Install the antenna at the farthest point from control modules.
Install the antenna fe ...