Inspecting Brake/Clutch Fluid Level
WARNING
If the brake/clutch fluid level is low, have the brakes inspected:
A low brake/clutch fluid level is dangerous. A low level could indicate brake lining wear or a brake system leak which could cause the brakes to fail and lead to an accident.
The brakes and clutch draw fluid from the same reservoir.
Inspect the fluid level in the reservoir regularly. It should be kept between the MAX and MIN lines.
The level normally drops with accumulated distance, a condition associated with wear of brake and clutch linings. If it is excessively low, have the brake/clutch system inspected by an Authorized Mazda Dealer.

Inspecting Coolant Level
Washer FluidMazda 6 Owners Manual: Radar Sensor (Front) (Some models)
Your vehicle is equipped with a radar sensor (front).
The following systems also use the radar sensor (front).
Distance Recognition Support System (DRSS)
Mazda Radar Cruise Control (MRCC)
Smart Brake Support (SBS)
The radar sensor (front) functions by detecting the radio waves reflected ...
Mazda 6 Owners Manual: Theft-deterrent control module inspection
1. Remove the theft-deterrent control module without disconnecting the
connectors.
2. Measure the voltage at the theft-deterrent control module terminals as
indicated below.
3. Disconnect the theft-deterrent control module connector before inspecting
for continuity at terminals L, Q, S, T, a ...