Mazda 6 Service Manual: No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

No.19 excessive shift shock on torque converter clutch (tcc)

No.21 noise occurs at idle when vehicle is stopped in d, s, l ranges, or in r position

Other materials:

Mazda 6 Service Manual: Gear Shift Indicator (GSI)
The Gear Shift Indicator (GSI) supports you to obtain optimum fuel economy and smooth driving. It displays the selected gear position in the instrument cluster as well as notifies the driver to change to the most suitable gear position corresponding to the actual driving condition. CAUTIO ...

Mazda 6 Service Manual: Symptom troubleshooting
Verify the symptoms, and perform troubleshooting according to the appropriate number. Vehicles with ABS/TCS Vehicles with DSC *1 : DSC system contains traction control function, DSC indicator light goes on and off while DSC operates. *2 : DSC indicator light goes on and off while D ...