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.

Specification

Egr valve inspection
Three-way catalytic converter (twc) inspectionMazda 6 Service Manual: Dsc on-board diagnosis
On-Board Diagnostic (OBD) Test Description
(See ABS (ABS/TCS) ON-BOARD DIAGNOSIS)
DTC Table
PID/DATA Monitor Table
Active Command Modes Table
...
Mazda 6 Service Manual: Viewing the Display
Guide lines which indicate the width of the vehicle (yellow) are displayed on
the screen as a reference to the approximate width of the vehicle in comparison
to the width of the parking space you are about to back into.
Use this display view for parking your vehicle in a parking space or garage ...