When it's time to change the oil in your Civic, the maintenance light (orange wrench) will appear on your dash, as well as a B1 message, showing an oil life of 15% or less.

To reset the Oil Life % gauge, press and hold the SEL/RESET button for about 10 seconds until the Oil Life message begins to flash. Release the SEL/RESET button, and hold it again for about 5 seconds until the Oil Life % resets to 100.