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

Ambient temperature sensor removal/installation
Cabin temperature sensor removal/installationMazda 6 Service Manual: Cleaning the Floor Mats
Rubber floor mats should be cleaned with mild soap and water only.
WARNING
Do not use rubber cleaners, such as tire cleaner or tire shine, when cleaning
rubber floor mats: Cleaning the rubber floor mats with rubber cleaning products
makes the floor mats slippery. This may cause an accident whe ...
Mazda 6 Service Manual: Dtc b1318
Caution
When attaching the tester lead to the ABS (ABS/TCS) HU/CM harness
connector, the SST (49 G066 001) must be used. (See ABS (ABS/TCS) HU/CM
INSPECTION.)
Diagnostic procedure
...