Why does low coolant lite stay on?

What is your question?

95 olds cutlass supreme 3.1L, replaced low coolant sensor, dash lite stays on. Sensor on radiator side. Changed rad fluid, bled air, full coolant level. "low coolant" lite stays on. Why?

What makes this problem better or worse?

After driving for 5 min. lite goes out.

How long has your 1995 Oldsmobile Cutlass Supreme had this problem?

Months.