Honda 1998 Prelude Owner's Manual page 59

Gauges
Maintenance Required Indicator
SLOT INDICATOR
This indicator reminds you that it is
nearing 7,500 miles (12,000 km)
since the last scheduled maintenance.
Refer to the Maintenance Schedules
for Normal and Severe Driving
Conditions on pages 164
Instruments and Controls
When the distance driven since the
last scheduled maintenance nears
7,500 miles (12,000 km), the
indicator will turn yellow. If you
exceed 7,500 miles (12,000 km), the
indicator will turn red.
Your dealer will reset the indicator
when he performs the scheduled
maintenance. If someone else
performs the maintenance, reset the
indicator by inserting your master or
valet key in the slot beside the
indicator.
— 168.