Operation from inside
To lock any door from the inside, press the door-lock knob.
To unlock, pull it outward. This does not operate the other door locks.

NOTE
The red indication can be seen when the door-lock knob is unlocked.

Operation from outside
To lock the rear and front passenger doors with the door-lock knob from the outside, press the door-lock knob to the lock position and close the door (holding the door handle in the open position is not required).This does not operate the other door locks.
This does not operate the other door locks.

NOTE
When locking the door this way:
Auto Lock/Unlock Function
Rear Door Child Safety LocksMazda 6 Owners Manual: Dtc c1148, c1158, c1168, c1178, c1233, c1234, c1235, c1236
Caution
When attaching the tester lead to the ABS (ABS/TCS) HU/CM harness
connector, the SST (49 G066 001) must be used. (See ABS (ABS/TCS) HU/CM
INSPECTION.)
Diagnostic procedure
...
Mazda 6 Owners Manual: Smart City Brake Support (SCBS)
The Smart City Brake Support (SCBS) system alerts the driver of a possible collision
using an indication in the display and a warning sound when the Forward Sensing
Camera (FSC) detects a vehicle ahead and determines that a collision with a vehicle
ahead is unavoidable while the vehicle is bei ...