fuel gauge not right. how to fix on 1999 Cadillac DeVille

reads 16 or 17 gallons all the time. when it gets low, the low light does come on. how to fix.

Asked by for the 1999 Cadillac DeVille
check and replace sending unit
1 more answer
This happened on my 99 deville and my mechanic simply reset the computer by pushing a couple of buttons on the dash around the heater controls. I am not an expert, but if you can find which buttons to hit it is an easy fix.