My fuel gauge drops when yhe check gauge light comes on car still runs with no issues

Hello, you could have a gauge issue, a sending unit issue (which provides data to the gauge based on the fuel level in the tank), or a wiring issue creating a loss of good data to the gauge. Testing will be need to command the gauge with a diagnostic tool to see if it responds as commanded consistently. Then, checking the fuel sending unit and wiring is necessary to get to the source of the concern. https://repairpal.com/repair-shops/chevrolet-repair-and-service-in-sparks-nevada

IF scan tool reads same as gauge - fuel tank sender is defective.. IF scan tool reads differently - the gauge is defective.