High Fuel Level alarms are required by government regulations to prevent the overfilling of a fuel tank. The alarm should activate when the fuel tank reaches between 90 and 95 percent capacity. This lets the person fueling the tank know when they should stop filling. There is normally nothing wrong with the generator when this alarm activates. On rare occasions the natural thermal expansion of the fuel will cause the alarm to activate. This will usually occur on an extremely hot summer day. High fuel level alarms may or may not clear themselves when the fuel level drops below the set point. You may have to manually reset the alarm when the fuel level drops.