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: Shift-Lock System
The shift-lock system prevents shifting out of P unless the brake pedal is depressed. To shift from P: 1. Depress and hold the brake pedal. 2. Start the engine. 3. Press and hold the lock-release button. 4. Move the selector lever. NOTE When the ignition is switched to ACC or the ignition ...

Mazda 6 Service Manual: Expansion valve removal/installation
1. Disconnect the negative battery cable. 2. Discharge the refrigerant from the system. (See RECOVERY.) (See CHARGING.) Caution If moisture or foreign material enters the refrigeration cycle, cooling ability will be lowered and abnormal noise will occur. Always immediately plug open fitt ...