A Coolant temperature sensor or sender will NOT prohibit the car from starting, Capri306, check out the thread here titled 'what not to do", I think you need to read that.
A sensor cannot "stick", they work off of a range of voltage, usually 0-1 volt, or 0-5 volts, if they get old, they go what FORD calls "out of range" and can no longer do there job, a code will be flagged. The computer makes decisions based on those voltage readings and a host of other readings as well. I'm not slammin' you, I'm trying to help you.