Insufficient coolant temperature for closed loop fuel control? What does this mean?

I have a Lincoln Town car that keeping having an error code come up and this is what it says. What does this mean? Is the thermostat going bad or what?Insufficient coolant temperature for closed loop fuel control? What does this mean?
most likely t-stat, replace and have cooling system flushed. also verify that temp sensor is working properly.





in order for a car to go into closed loop operation where emissions performance is best the computer needs to see at least 3 things.





coolant temp at certain value, usually over 150 F


oxygen sensor switching properly


and certain amount of time vehicle has been running.