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: Essential Information
Introduction
Be careful not to hurt yourself when inspecting your vehicle, replacing a tire,
or doing some kind of maintenance such as car washing.
In particular, wear thick work gloves such as cotton gloves when touching areas
that are difficult to see while inspecting or working on your vehi ...
Mazda 6 Service Manual: No.2 amount of air blown from vents does not change
Full-auto Air Conditioner
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while performing the inspection to discover
whether poor contact points are the cause of any intermittent malfunctions.
If there is a problem, check to mak ...