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

Air filter removal/installation
A/c unit removal/installationMazda 6 Service Manual: Dual proportioning valve inspection (without abs)
1. Connect the SSTs to the brake pipes as shown in the figure.
2. Bleed the air from the brake system.
3. Measure the fluid pressure of the master cylinder and the rear brake.
If not within the specification, replace the dual proportioning valve.
Fluid pressure
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Mazda 6 Service Manual: Blind Spot Monitoring (BSM) (Some models)
The Blind Spot Monitoring (BSM) is designed to assist the driver in checking
the area to the rear of the vehicle on both sides during lane changes by notifying
the driver of the presence of vehicles approaching from the rear in an adjacent
lane.
The Blind Spot Monitoring (BSM) detects vehicle ...