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

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Mazda 6 Service Manual: Service cautions
HANDLING INSUFFICIENT REFRIGERANT LEVEL If an insufficient refrigerant level is detected at troubleshooting, do not charge (add) the refrigerant. Because an accurate amount of refrigerant cannot be determined from the pressure indicated on the manifold gauge, never charge the refrigeran ...

Mazda 6 Service Manual: Oil pressure switch inspection
Caution Water or foreign objects entering the connector can cause poor connection or corrosion. Be sure not to drop water or foreign objects on the connector when disconnecting it. On-vehicle Inspection (harness inspection) 1. Disconnect the negative battery cable. 2. Remove the under ...