2003 Pontiac Bonneville Owner's Manual - Page 169

On vehicles with a DIC, the CHECK GAGES LOW FUEL message will be displayed when the fuel gage reads in the yellow band. See DIC Warnings and Messages on page 3-60 for more information. Here are some things that owners ask about. None of these show a problem with your fuel gage: At the service station, the gas pump shuts off before the gage reads full. It takes a little more (or less) fuel to fill up than the gage indicated. For example, the gage may have indicated the tank was half full, but it actually took a little more (or less) than half the tank's capacity to fill the tank. Boost Gage Vehicles equipped with the supercharged engine have this boost gage that indicates vacuum during light to moderate throttle and boost under heavier throttle. The gage displays the air pressure level going into the engine's combustion chamber. The gage is automatically centered at zero every time the ignition key is turned to ON. Actual vacuum or boost is displayed from this zero point. Changes in ambient pressure, such as driving in mountains and changing weather, will slightly change the zero reading. 3-54