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: Owner Maintenance Precautions
The owner or a qualified service technician should make these vehicle inspections
at the indicated intervals to ensure safe and dependable operation.
Bring any problem to the attention of an Authorized Mazda Dealer or qualified
service technician as soon as possible.
At Least Twice a Year (For ...
Mazda 6 Service Manual: Door Locks
WARNING
Always take all children and pets with you or leave a responsible person
with them: Leaving a child or a pet unattended in a parked vehicle is dangerous.
In hot weather, temperatures inside a vehicle can become high enough to cause brain
damage or even death.
Do not leave the key in ...