Take the appropriate action and verify that the warning light turns off.

Taking Action
Message Indicated on DisplayMazda 6 Owners Manual: Oil pressure switch removal/installation
Warning
When the transaxle and ATF are hot, they can badly burn. Turn off
the engine and wait untill they are cool before replacing ATF.
1. Disconnect the negative battery cable.
2. Remove the under cover.
3. Disconnect the cord assembly connector.
4. Remove the oil pressure switch.
...
Mazda 6 Owners Manual: Service procedure
Inspection, adjustment
Inspection and adjustment procedures are divided into steps. Important
points regarding the location and contents of the procedures are explained
in detail and shown in the illustrations.
Repair procedure
1. Most repair operations begin with an overview illustr ...