My old Iron Barrel has no fuel guage of any sort, but if a low level light is in an "always on" state or level meter needle stuck at "E", I'd suspect a wonky fuel level sender in the tank.
A search of the Forum Archives reveals that problems with the OEM senders across UCE models are fairly common. The float can detach, get fuel-logged or just get stiff, especially if it sits or has sat around for long periods.
There have been different types of senders used in various UCE engines of both lever and bob types. Our Forum hosts can certainly square you away with the right one for your bike. Just email them for guidance.
Or, you can just rock it "Old School", ignore or tape over the light if it bugs you, and simply fuel up every 100 miles or so. If it's just a stiff float or actuator arm pivot, it may sort of "fix itself" with more frequent use, and a little SeaFoam or Marvel Mystery Oil (an ounce or two per tankful) in the fuel, as "AzCal Retread" suggests, may help hasten its easing up, and wouldn't do the rest of your ride any harm.