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: Idle air control (iac) valve inspection
Note
Perform the following inspection only when directed.
Operation Test
Carry out the Idle Air Control Inspection. (See Idle Air Control System
Inspection.)
If not as specified, perform the further inspection for the IAC valve.
Resistance Inspection
1. Disconnect the negative batt ...
Mazda 6 Owners Manual: Exhaust system
EXHAUST SYSTEM INSPECTION
Start the engine and inspect each exhaust system component for exhaust gas
leakage.
If leakage is found, repair or replace as necessary.
EXHAUST SYSTEM REMOVAL/INSTALLATION
Warning
When the engine and exhaust system are hot, they can badly burn.
Turn off t ...