If your vehicle rapidly closes in on the vehicle ahead because the vehicle applies the brakes suddenly while you are traveling in headway control, the warning sound activates and the brake warning is indicated in the display. Always verify the safety of the surrounding area and depress the brake pedal while keeping a safer distance from the vehicle ahead.
Additionally, always keep a safer distance from the vehicles behind you.

Mazda Radar Cruise Control (MRCC) Display Indication
Setting the SystemMazda 6 Owners Manual: Brake pedal removal/installation
1. For ATX model, remove the lock unit with brake switch (R.H.D. only).
2. Remove in the order indicated in the table.
3. Install in the reverse order of removal.
Brake switch Installation Note
1. Fix the brake switch on a bracket with pressing down at 50 N {5.1 kgf·m,
37 ft·lbf}.
2. Ro ...
Mazda 6 Owners Manual: Joint shaft removal/installation
Caution
Performing the following procedures without first removing the ABS
wheel-speed sensor may possibly cause an open circuit in the harness if it
is pulled by mistake. Before performing the following procedures, remove the
ABS wheel-speed sensor and fix it to an appropriate place wh ...