1. Remove the air filter.
2. Inspect the air filter.
Note

Air filter removal/installation
A/c unit removal/installationMazda 6 Service Manual: Operating Tips
Operate the climate control system with the engine running.
To prevent the battery from being discharged, do not leave the fan control
dial/switch on for a long period of time with the ignition switched ON when
the engine is not running.
Clear all obstructions such as leaves, snow and i ...
Mazda 6 Service Manual: Dtc b1318
Caution
When attaching the tester lead to the ABS (ABS/TCS) HU/CM harness
connector, the SST (49 G066 001) must be used. (See ABS (ABS/TCS) HU/CM
INSPECTION.)
Diagnostic procedure
...