If a radio system is installed improperly or if a high-powered type is used, the CIS and other systems may be affected. When the vehicle is to be equipped with a radio, observe the following precautions:
SstMazda 6 Service Manual: Pcv valve inspection
1. Disconnect the negative battery cable.
2. Remove the intake maniforld.(see INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)
3. Remove the PCV valve.
4. Blow through the valve and verify that air flows as specified.
If not as specified, replace the PCV valve.
Specification
...
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 ...