Displays in the following cases:

Stop Vehicle in Safe Place Immediately
Message Indicated in Multi-information DisplayMazda 6 Owners Manual: Front/rear abs wheel-speed sensor inspection
Visual Inspection
Remove the wheel and tire, and inspect the sensor for looseness and damage.
Replace the sensor if necessary.
Clearance Inspection
Inspect the clearance between the wheel-speed sensor and the sensor rotor.
Clearance
0.3-1.1 mm {0.012-0.043 in}
Resistance Inspection
...
Mazda 6 Owners Manual: Engine coolant
ENGINE COOLANT LEVEL INSPECTION
Verify that the coolant level in the coolant reservoir is between the F and L
marks.
If the engine coolant level is below L, remove the radiator cap and add
coolant. (See COOLING SYSTEM SERVICE WARNINGS.)
ENGINE COOLANT REPLACEMENT
Warning
Drain the ...