1. Measure the wear of the diaphragm spring fingers.
Depth
0.6 mm {0.024 in} max.

2. Measure the flatness of the pressure plate with a straight edge and a feeler gauge.
Maximum clearance 0.5 mm {0.020 in}

3. When checking the diaphragm spring fingers, mount a dial indicator on the cylinder block.
4. Rotate the flywheel and check for misaligned diaphragm spring fingers.
Misalignment
0.6 mm {0.024 in} max.

Clutch unit removal/installation
Clutch disc inspectionMazda 6 Service Manual: Manual Shift Mode
The manual shift mode gives you the feel of driving a manual transaxle vehicle
by allowing you to operate the selector lever manually. This allows you to control
engine rpm and torque to the drive wheels much like a manual transaxle when more
control is desired.
To change to manual shift mode ...
Mazda 6 Service Manual: Front/rear abs wheel-speed sensor inspection
Visual Inspection
Remove the wheel and tire, and inspect the sensor for looseness and damage.
Replace the sensor if necessary.
Clearance Inspection
Inspect the clearance between the wheel-speed sensor and the sensor rotor.
Clearance
0.3-1.1 mm {0.012-0.043 in}
Resistance Inspection
...