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: Instrument cluster configuration
1. Connect the SST (WDS or equivalent) to the DLC-2.
2. Input vehicle information following the directions on the screen.
3. Select Module programming.
4. Select Programmable module installation.
5. Select the following items and perform procedures according to directions
on the screen.
...
Mazda 6 Owners Manual: Crankshaft position (ckp) sensor inspection
Note
Perform the following inspection only when directed.
Resistance Inspection
1. Disconnect the CKP sensor connector.
2. Measure the resistance between CKP sensor terminals A and B using an
ohmmeter.
If not as specified, replace the CKP sensor.
If CKP sensor resistance is okay, bu ...