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

Taking Action
Message Indicated on DisplayMazda 6 Owners Manual: Gear Shift Indicator (GSI)
The Gear Shift Indicator (GSI) supports you to obtain optimum fuel economy and
smooth driving. It displays the selected gear position in the instrument cluster
as well as notifies the driver to change to the most suitable gear position corresponding
to the actual driving condition.
CAUTIO ...
Mazda 6 Owners Manual: Inspecting Coolant Level
WARNING
Do not use a match or live flame in the engine compartment. DO NOT ADD
COOLANT WHEN THE ENGINE IS HOT: A hot engine is dangerous. If the engine has
been running, parts of the engine compartment can become very hot. You could be
burned. Carefully inspect the engine coolant in the coola ...