Coolant sensor 96 Saturn sl1? It's overheating changed thermostat ,resivior ,water pump flushed radiator , compression test we're good??

Kinda sounds like you still have air in your cooling system. You will have to air bleed the system.

How hot is it getting in degrees F? Some electric fans won't even turn on, till around 220 degrees F. Does the fan turn on at all?
As far as overheating, does the coolant recovery reservoir fill up in a hurry?
Sometimes after opening up the cooling system, you get air in the system that may cause temp gage to react.
What about your thermostat? Did you check for coolant flow through the radiator? Another thought might be a head gasket issue, I'd check everything else first.

Of the water is boiling them it has run hot. There is no way around this fact. Get a compression test done first. This should reveal if any damage has been done. Then address the boiling off problem. This can be a air pocket in the line, incorrect anti freeze mixture, sticking thermostat, water pump, cap, etc.

Not exactly sure what a "resivior" is, do you mean reservoir? If so it sounds like you have a blockage in your coolant hoses somewhere or possibly your radiator. Try a coolant pressure test

The most common cause is low coolant level, so check the radiator and overflow tank and fill as needed. If coolant is over 2 years old, it is a good idea to change the coolant and thermostat-start afresh.
Check the radiator cap. If it doesn't hold pressure of about 13-15 psi in the coolant system, the seal is bad and a new radiator cap is called for. The coolant system is a sealed system, so you should never have to add coolant, save for a small loss through evaporation in the overflow tank. If you are losing coolant, there must be a leak that needs found and repaired-a pressure test of the system should show up a leak.
When the engine is warmed up, the thermostat opens and coolant is circulated through the engine (pushed by the water pump on the front of the engine), into the upper radiator hose to the radiator, and down through the radiator where it is cooled, then back to engine and water pump through the lower radiator hose-a continuous circulation. If anything blocks this circulation (like a partially plugged radiator, or leaves, trash or debris on the outside of the radiator preventing good radiator cooling) then you could get engine overheating. You may want to have the coolant circulation checked, and/or have the radiator and engine flushed. Also possible that the water pump may not be promoting good flow-the impellers on the pump may be worn down to stubs-this can happen if regular maintenance is not observed.
Your radiator fans should also be checked that they work when called for.
The worst case would be a blown cylinder head gasket-another common cause of overheating, and the most expensive fix. A compression test could check for this condition- a cylinder or two with low compression indicates head gasket failure. Coolant can get mixed in with the oil, or it may wind up in the cylinders and get burned, putting out white smoke out the exhaust.
Overheating is bad on engines, get it checked right away.

Probably head gasket... not a hard fix... can have a compression check to make sure.

replace thermostat and radiator pressure cap, what i would do is flush out the coolant system go auto parts store buy a radiator flush kit replace water pump do all this see what happen you need to add 50/50 antifreeze and water to coolant system.

yes. the impellor on these engines have a tendency to come off the water pump.First you can see if the pump is working by removing a heater hose then have someone to start the engine. if the water sprays a good, solid stream out then the water pump is good. if the water just barely comes out or not at all then the pump is weak or "bad".

clogged radiator,fan not cooling ,stat or pump even though defective belt slipping on pump

Try blowing the radiator fins out (from the inside) with compressed air--bugs and other debris can clog the air flow. Do the radiator fan(s) run when hot? If not, check for blown fuse, seized fan motor(s), bad relay, or bad engine thermal sensor. Is it losing coolant water from somewhere?