1. Measure the temperature around the water temperature sensor.
2. Measure the resistance between terminals of the water temperature sensor.

Water temperature sensor removal/installation
Refrigerant pressure switch removal/installationMazda 6 Service Manual: Engine coolant temperature (ect) sensor inspection
Note
Perform the following inspection only when directed.
ECT Sensor Resistance Inspection
1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.)
2. Remove the ECT sensor (located above the starter).
3. Place the ECT sensor in water with a thermometer, and heat the water
gra ...
Mazda 6 Service Manual: Clutch switch inspection
Note
Perform the following inspection only when directed.
Continuity Inspection
1. Verify that the clutch switch is installed properly.
2. Disconnect the negative battery cable.
3. Remove the clutch switch.
4. Inspect for continuity between the clutch switch terminals using an
ohmmeter. ...