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

Cabin temperature sensor removal/installation
Evaporator temperature sensor removal/installationMazda 6 Service Manual: Control Switches
AUTO switch
By pressing the AUTO switch the following functions will be automatically controlled
in accordance with the selected set temperature:
Airflow temperature
Amount of airflow
Selection of airflow mode
Outside/Recirculated air selection
Air conditioner operation
NOTE
AUTO ...
Mazda 6 Service Manual: Rear Cross Traffic Alert (RCTA) (Some models)
The Rear Cross Traffic Alert (RCTA) system is designed to assist the driver in
checking the area to the rear of the vehicle on both sides while the vehicle is
reversing by alerting the driver to the presence of vehicles approaching the rear
of the vehicle.
The Rear Cross Traffic Alert (RCTA) ...