Often the problems can be as simple as a bad connection. Unplug the sensor check terminals for corrosion. and plug in the sensor it might do the trick.
Maybe sticking float caused by crystallization of the fluid.
Pull the sensor unit out of the tank and clean it thoroughly with hot water.
Make sure the float is free.
This pdf might help.
https://static.nhtsa.gov/odi/tsbs/2014/SB-10046782-4244.pdf