1. Verify that the joint shaft is not twisted or cracked.
2. Turn the joint shaft by hand and verify that the bearing rotates smoothly and freely.

Drive shaft
Joint shaft removal/installationMazda 6 Service Manual: Locking, Unlocking the Doors
NOTE
The system may not operate if you are too close to the windows or door
handles.
If the key is left in the following areas and you leave the vehicle,
the doors may be locked depending on the radio wave conditions even if the key
is left in the vehicle.
Around the dashboard
...
Mazda 6 Service Manual: Operating Tips for CD Player
Condensation phenomenon
Immediately after turning on the heater when the vehicle is cold, the CD or optical
components (prism and lens) in the CD player may become clouded with condensation.
At this time, the CD will eject immediately when placed in the unit. A clouded CD
can be corrected sim ...