What is the red light under the fuel gauge on a 2001 Subaru Forester not the low fuel light the red light under the fuel light on the dash it is on all the time?

The red light under the fuel gauge on a 2001 Subaru Forester typically indicates a malfunction with the fuel gauge or the fuel system, such as a problem with the fuel level sensor. It may also signal an issue with the fuel pump or related electronics. If it remains illuminated consistently, it is advisable to have the vehicle inspected by a qualified mechanic to diagnose and resolve the underlying issue.