Dtc 15
ForewordMazda 6 Service Manual: Manually Shifting Up
   You can shift gears up by operating the selector lever or the steering shift 
switches (some models).
M1 → M2 → M3 → M4 → M5 → M6
Using selector lever
To shift up to a higher gear, tap the selector lever back (+) once.
Using steering shift switch (some models)
To  ...
   
Mazda 6 Service Manual: Steering wheel and column inspection
   Steering Wheel Play Inspection
With the wheels in the straight-ahead position, gently turn the steering 
wheel to the left and right and verify that the play is within the 
specification.
	If the play exceeds the specification, either the steering joints are 
	worn or the backlash of the stee ...