Overheating?

[jvmbc4]

So I replaced the coolant cap with the new one I received today and the light still blinks from the moment I start the engine. I guess I will try to find a thermo sensor for the engine compartment. Has anyone ever had to replace one of these. I have not been able to find one when I search for parts.

1) The coolant was low three times after refilling it, so I plan on getting a new coolant cap.
2) The drivers side cooling fan works on both low and high speed, while the an on the passenger side is only working at high speed. I checked the relays and they are all good. Do I need to change out this fan?
3) The engine compartment fan is working, I jumped the relay. Can the thermo sensor go bad?
4) Water pump and thermostat have 20,000 miles in 9 years. should I change them out?