Buick 2005 LeSabre Owner's Manual page 156

Service Vehicle Soon Light
These problems may not be obvious and may affect
vehicle performance or durability. Consult a qualified
dealership for necessary repairs to maintain top
vehicle performance.
This light will come on briefly when the ignition is turned
on to show that it is working properly.
3-46
This light will come on and
stay on if your vehicle has
certain non-emission
related problems.
Fuel Gage
United States
The fuel gage shows about how much fuel is in your
tank. It works only when the ignition is on. When
the indicator moves to the edge of the low fuel warning
band, the low fuel warning light will come on and a
chime will sound. You still have a little fuel left, but you
need to get more fuel right away.
Canada