Mazda 6 Service Manual: No.19 exhaust smoke

No.18 cooling system concerns-runs cold

No.20 fuel odor (in engine compartment)

Other materials:

Mazda 6 Service Manual: Engine control system operation inspection
Main Relay Operation Inspection Verify that the main relay clicks when the ignition switch is turned to ON position and off. If there is no operation sound, inspect the following. - Main relay (See RELAY INSPECTION.) - Harness and connector between ignition switch and main relay termi ...

Mazda 6 Service Manual: To Resume Cruising Speed at More Than 25 km/h (16 mph)
If some other method besides the OFF/ CANCEL switch was used to cancel cruising speed (such as applying the brake pedal) and the system is still activated, the most recent set speed will automatically resume when the RESUME/ switch is pressed. If vehicle speed is below 25 km/h (16 mph), incre ...