Take the appropriate action and verify that the warning light turns off.

Taking Action
Message Indicated on DisplayMazda 6 Owners Manual: Overheating
If the high engine coolant temperature warning light turns on, the vehicle loses
power, or you hear a loud knocking or pinging noise, the engine is probably too
hot.
WARNING
Pull over to a safe location,
then switch the ignition off and make sure the fan is not running before attempting
t ...
Mazda 6 Owners Manual: Dtc clearing procedure
1. Start the on-board diagnostic test mode.
2. First press the POWER button, then simultaneously press AUDIO CONT button
for 2 seconds or more.
Caution
Before clearing the DTCs, be sure to enter all of them displayed
in the on-board diagnostic test mode in the Audio Repair Order Form. ...