1. Remove the evaporative gas check valve (one-way).
2. Apply pressure to port A, and verify that there is no airflow.
3. Apply negative pressure to port A, and verify that there is air flow.

Charcoal canister inspection
Purge solenoid valve removal/installationMazda 6 Service Manual: Installation of radio system
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:
Install the antenna at the farthest point from control modules.
Install the antenna fe ...
Mazda 6 Service Manual: Intermittent concern troubleshooting
Vibration Method
1. If malfunction occurs or becomes worse while driving on a rough road or
when engine is vibrating, perform the steps below.
Note
There are several reasons vehicle or engine vibration could cause
an electrical malfunction. Some of the things to check for are:
...