1. Remove the drive belt. (See DRIVE BELT REPLACEMENT.)
2. Verify that the drive belt auto tensioner moves smoothly in the operational direction.

3. Turn the drive belt auto tensioner pulley by hand and verify that it rotates smoothly.
4. Install the drive belt. (See DRIVE BELT REPLACEMENT.)
Drive belt replacement
Valve clearanceMazda 6 Service Manual: Air intake actuator inspection
1. Connect battery positive voltage to terminal D or F and ground to terminal
F or D of the air intake actuator.
2. Verify that the air intake actuator operates as shown below.
If not as specified, replace the air intake actuator.
...
Mazda 6 Service Manual: Foreword
Outline
There are two on-board diagnostic functions: Operation mode, which
inspects for and indicates correct operation of the input signals to the
control module, and condition detection mode, which indicates troubles in
the system.
The two functions can be done using either of the f ...