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: Overheating
If the high engine coolant temperature warning light turns on, the vehicle loses power, or you hear a loud knocking or pinging noise, the engine is probably too hot. WARNING Pull over to a safe location, then switch the ignition off and make sure the fan is not running before attempting t ...

Mazda 6 Service Manual: Transaxle range (tr) switch inspection
Operating Inspection 1. Verify that the starter operates only when the ignition switch is at the START position with the selector lever in P or N position. If not as specified, adjust the TR switch. 2. Verify that the back-up lights illuminate when shifted to R position with the ignition ...