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: 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 ...
Mazda 6 Service Manual: Foreword
Caution
When the engine does not start or stalls and the following DTCs
are not indicated, go to engine symptom troubleshooting.
Note
When the immobilizer system is defective, the engine cannot be
started.
If engine condition is normal but light stays on, inspect for
short circ ...