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: Underbody Maintenance
Road chemicals and salt used for ice and snow removal and solvents used for dust
control may collect on the underbody. If not removed, they will speed up rusting
and deterioration of such underbody parts as fuel lines, frame, floor pan, and exhaust
system, even though these parts may be coated ...
Mazda 6 Owners Manual: Steering gear and linkage inspection
Rack Inspection
1. Inspect the rack for cracking, damage, and tooth wear. Replace it as
necessary.
2. Measure the runout of the rack.
Runout
Near point A: 0.15 mm {0.006 in} max.
Near point B: 0.20 mm {0.008 in} max.
3. If not within the specification, replace the rack.
Tie-rod End ...