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: Crankshaft position (ckp) sensor inspection
Note Perform the following inspection only when directed. Resistance Inspection 1. Disconnect the CKP sensor connector. 2. Measure the resistance between CKP sensor terminals A and B using an ohmmeter. If not as specified, replace the CKP sensor. If CKP sensor resistance is okay, bu ...

Mazda 6 Service Manual: Engine coolant
ENGINE COOLANT LEVEL INSPECTION Verify that the coolant level in the coolant reservoir is between the F and L marks. If the engine coolant level is below L, remove the radiator cap and add coolant. (See COOLING SYSTEM SERVICE WARNINGS.) ENGINE COOLANT REPLACEMENT Warning Drain the ...