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: Door lock timer unit removal/installation
1. Disconnect the negative battery cable.
2. Remove the glove compartment. (L.H.D.)
3. Remove the bolt.
4. While inclining the door lock timer unit along the body panel in the
direction indicated by the arrow, disengage the bracket hook from the hole in
the body panel.
5. Disconnect the do ...
Mazda 6 Owners Manual: Theft-deterrent control module inspection
1. Remove the theft-deterrent control module without disconnecting the
connectors.
2. Measure the voltage at the theft-deterrent control module terminals as
indicated below.
3. Disconnect the theft-deterrent control module connector before inspecting
for continuity at terminals L, Q, S, T, a ...