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: Intermittent concern troubleshooting
Vibration Method
1. If malfunction occurs or becomes worse while driving on a rough road or
when engine is vibrating, perform the steps below.
Note
There are several reasons vehicle or engine vibration could cause
an electrical malfunction. Some of the things to check for are:
...
Mazda 6 Owners Manual: Curtain air bag module removal/installation
Warning
Handling the air bag module improperly can accidentally deploy the air bag
module, which may seriously injure you. Read AIR BAG SYSTEM SERVICE WARNINGS
before handling the air bag module. (See SERVICE WARNINGS.)
1. Turn the ignition switch to LOCK position.
2. Disconnect the nega ...