WARNING
Always adjust the audio while the vehicle is stopped:
Do not adjust the audio control switches while driving the vehicle. Adjusting the audio while driving the vehicle is dangerous as it could distract your attention from the vehicle operation which could lead to a serious accident.
Even if the audio control switches are equipped on the steering wheel, learn to use the switches without looking down at them so that you can keep your maximum attention on the road while driving the vehicle.
CAUTION
For the purposes of safe driving, adjust the audio volume to a level that allows you to hear sounds outside of the vehicle including car horns and particularly emergency vehicle sirens.
NOTE
Do not spill any liquid on the audio system.

Do not insert any objects, other than CDs, into the slot.

Radio ReceptionMazda 6 Owners Manual: Diagnostic assist function
Structural View
Switch location
LCD Inspection
1. With audio on, first press the POWER button, then simultaneously press the
SEEK button (upper) for approximately 1 second.
2. Inspect the LCD according to the following table:
3. Turn the audio off or the ignition switch to the LOCK posi ...
Mazda 6 Owners Manual: Rear door speaker removal/installation
1. Disconnect the negative battery cable.
2. Remove the rear door trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
Rear Door Speaker Installation Note
Attach the speaker with the wiring harness placed in the groove of the door
unit panel.
...