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: Constant Monitoring
The following components of the air bag systems are monitored by a diagnostic
system:
Crash sensors, and diagnostic module (SAS unit),
Front air bag sensors
Air bag modules
Side crash sensors
Air bag/Front seat belt pretensioner system warning light
Front seat belt pretensioners
Re ...
Mazda 6 Service Manual: Cargo compartment light switch inspection
1. Remove the liftgate lower trim. (See LIFTGATE LOWER TRIM
REMOVAL/INSTALLATION)
2. Disconnect the cargo compartment light switch connector.
3. Inspect for continuity between the cargo compartment light switch
terminals using an ohmmeter.
If not as specified, replace the liftgate lock.
...