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

Air filter removal/installation
A/c unit removal/installationMazda 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
...
Mazda 6 Service Manual: Control valve body removal
On-Vehicle Removal
Warning
Using compressed air can cause dirt and other particles to fly
out, causing injury to the eyes. Wear protective eyes whenever using
compressed air.
Caution
Clean the transaxle exterior throughout with a steam cleaner or
cleaning solvents before removal ...