Fuel Gage
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The instrument panel cluster (IPC) displays the fuel level as determined by the powertrain control module (PCM)/engine control module (ECM). The IPC receives a Class 2 message from the PCM/ECM indicating the fuel tank level remaining. The fuel gage defaults to empty if the PCM/ECM detects a malfunction in the fuel level sensor circuit or the IPC detects a loss of class 2 communication with the PCM/ECM.
When the fuel level is below a pre-determined value, the low fuel indicator/message is displayed in the IPC.