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: Master cylinder disassembly/assembly
Caution
If the master cylinder body is damaged, replace the unit as a
component. When securing the master cylinder in a vise, tighten only the
flange of the master cylinder.
1. Disassemble in the order indicated in the table.
2. Assemble in the reverse order of disassembly.
Stop ...
Mazda 6 Owners Manual: Side protector removal
1. Pry the side protector end 20-30 mm {0.8-1.1 in} using a flathead
screwdriver or a razor.
Warning
Using a razor with bare hands can cause injury. Always wear gloves
when using a razor.
Note
The side protector is installed with double-sided adhesive tape.
If the side protector ...