Depress the button on the seat belt buckle. If the belt does not fully retract, pull it out and check for kinks or twists. Then make sure it remains untwisted as it retracts.

NOTE
If a belt does not fully retract, inspect it for kinks and twists. If it is still not retracting properly, have it inspected at an Authorized Mazda Dealer.
Fastening the Seat Belt
Front Shoulder Belt AdjusterMazda 6 Owners Manual: Transmitter battery inspection
Caution
Since the battery voltage does not drop fully if the button is
pushed for only 4 seconds or less, it can not be properly examined to see
whether it is good or bad. Always push the button for 5 seconds.
Note
A correct measurement can not be obtained if the battery
temperat ...
Mazda 6 Owners Manual: Side Air Bags
The side air bags are mounted in the outboard sides of the front seatbacks.
When the air bag crash sensors detect a side impact of greater than moderate
force, the system inflates the side air bag only on the side in which the vehicle
was hit. The side air bag inflates quickly to reduce injury ...