Cadillac 2000 Catera Owner's Manual page 143

Low Fuel Light
The light may begin to flash as the fuel level gets lower.
It will also come on for a few seconds when you first
turn on the ignition as a check to show it's working.
If it doesn't come on then, have it fixed.
2-78
If the fuel level is low,
approximately one (3.8 L)
to two gallons (7.57 L) of
fuel remaining in the fuel
tank, a light will come on
until you add fuel.
Fuel Cap Indicator Light
You should recheck your fuel cap to make sure it
is on tight.
If you continue to drive with a loose fuel cap, the
diagnostic system in your vehicle can determine if the
fuel cap has been left off or improperly installed. A
loose or missing fuel cap will allow fuel to evaporate
into the atmosphere. If this happens, the CHECK
ENGINE light may come on. For more information, see
"Malfunction Indicator Lamp" earlier in this section.
This light will come on
if the fuel cap has not
been fully tightened, is
missing or has been
improperly installed.