All doors lock automatically when the lock side is pressed. They unlock when the unlock side is pressed.
Driver's door

Front passenger's door

To lock all the doors from an open front door, press the lock side of the door lock switch and then close the door.
NOTE
When locking the doors this way, be careful not to leave the key inside the vehicle.
Locking, Unlocking with Transmitter
Auto Lock/Unlock FunctionMazda 6 Owners Manual: Service warnings
Component Disassembly
Disassembling and reassembling the components of the air bag system
can render the system inoperative, which may result in serious injury or
death in the event of an accident. Do not disassemble any air bag system
components.
Wiring Harness Repair
Incorrec ...
Mazda 6 Owners Manual: Front door key cylinder removal/installation
1. Remove the front door unit.
2. Remove the cover, then remove the bolt.
3. For protector-equipped vehicles, pull out the protector tab from the latch
and remove the protector.
4. Disconnect the rod.
5. Remove the front outer handle.
6. Turn the key cylinder in the direction indicated by ...