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: 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 ...

Mazda 6 Service Manual: Dtc clearing procedure
1. Start the on-board diagnostic test mode. 2. First press the POWER button, then simultaneously press AUDIO CONT button for 2 seconds or more. Caution Before clearing the DTCs, be sure to enter all of them displayed in the on-board diagnostic test mode in the Audio Repair Order Form. ...