where can I find the fuel sensor on my cadillac, fuel level low and EXP 11 on on 1998 Cadillac DeVille

the car seems to be ok after we fill up with gas but after a 40/50 mile drive the fuel level shime come on and it keeps going telling me it low on fuel and also a EXP 11 shows up on screen, that bell drives me nutts, and I kow it has fuel but the bell keeps going, I haver tried to disconect the bell but can't find it,, how do I get solve the problem?

Asked by for the 1998 Cadillac DeVille