Turn the auxiliary key toward the front to lock, toward the back to unlock.
To lock
All doors lock automatically when the driver's door is locked using the auxiliary key.
To unlock
The driver’s door unlocks when the auxiliary key is turned briefly to the unlock position and then immediately returned to the center position.
All doors unlock when the driver's door is unlocked and the auxiliary key is held in the unlock position for one second or longer.

Door Locks
Locking, Unlocking with Request Switch, Door Handle (With the advanced keyless
function)Mazda 6 Owners Manual: Driver-side 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.)
Due to the adoption of 2-step deployment control in both the
driv ...
Mazda 6 Owners Manual: Dtc c1095, c1096
Caution
When attaching the tester lead to the DSC HU/CM connector the SST
(49 G066 004) must be used.
Diagnostic procedure
...