1. Insert a small screwdriver into the slot and gently pry open the transmitter.

2. Press the portion of the battery indicated by A and remove the battery.

3. Install a new battery (CR2025) into the front portion of the holder with the positive pole (+) facing up. Press on the B portion of the battery to set the battery.
4. Align the front and back covers and snap the transmitter shut.
Battery specification Lithium CR2025 × 1
Note

Door lock timer unit id code change
Transmitter battery inspectionMazda 6 Service Manual: Input/turbine speed sensor removal/installation
1. Disconnect the negative battery cable.
2. Remove the battery and battery tray.
3. Remove the air cleaner component. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
4. Disconnect the input/turbine speed sensor connector.
5. Remove the input/turbine speed sensor.
6. Apply ATF to a new O-ring ...
Mazda 6 Service Manual: Ignition switch inspection
1. Disconnect the negative battery cable.
2. Remove the column cover. (See COLUMN COVER REMOVAL/INSTALLATION)
3. Disconnect the ignition switch connectors.
4. Inspect for continuity between the ignition switch terminals using an
ohmmeter.
If not as specified, replace the ignition switch.
...