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: Essential Information
Introduction
Be careful not to hurt yourself when inspecting your vehicle, replacing a tire,
or doing some kind of maintenance such as car washing.
In particular, wear thick work gloves such as cotton gloves when touching areas
that are difficult to see while inspecting or working on your vehi ...
Mazda 6 Service Manual: Underbody Maintenance
Road chemicals and salt used for ice and snow removal and solvents used for dust
control may collect on the underbody. If not removed, they will speed up rusting
and deterioration of such underbody parts as fuel lines, frame, floor pan, and exhaust
system, even though these parts may be coated ...