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: Locking, Unlocking the Doors
NOTE
The system may not operate if you are too close to the windows or door
handles.
If the key is left in the following areas and you leave the vehicle,
the doors may be locked depending on the radio wave conditions even if the key
is left in the vehicle.
Around the dashboard
...
Mazda 6 Service Manual: Indication on Display
The Distance Recognition Support System (DRSS) operation status is indicated
in the active driving display or multi-information display. Regarding malfunctions,
check the vehicle conditions or have it inspected by an Authorized Mazda Dealer
according to the content of the displayed message.
R ...