Service C doesn't mean much by itself.
There should be another line indicating which services are due, like service 3, service 6, service 13, etc... They all indicate different items. You need to use the indicator to display the service menu. Read your owners manual to see how to display the service items.
Here, this is from the manual:
The maintenance Service Indicator displays the maintenance Service Code (letters A - H), which are due, in the multifunction display.
Interpreting The Service Code
The function of the Service Code (letters A - H) is to provide the driver with an approximate time necessary to perform the required "Service Item(s)" ranging from approximately one hour for a Service A to approximately eight hours for a Service H.
Service Items range from Service 1 through Service 20. There may be just 1 or there may be 3 or more Service Items; as many as the FSS PLUS system determines as necessary to complete at that time. They can vary by model and included Additional Work.
Up or down arrow in the display indicates additional items.
To view the actual "Service Item(s)" required, you must call up the "Service" menu in the multifunction display. Please refer to "Calling up the Correct Service item". See: Calling Up the Correct Service Item