Ford Repair: Ford F150 low coolant temp, coolant temp, clutch fan

Question
  My service engine light came on, I had a diagnostic performed and the code indicated low coolant temp.  My coolant fan comes on immediately upon startup and runs continuously.  I seem to have sufficient heat even at below 0 temps.  I have purchased a new thermostat and temp sensor.  Where is the sensor that controls the coolant fan located, and am I going in the right direction to repair this problem.  This is a 5.4L triton engine.  Seems to run fine but I think its using more fuel than normal. Also, after repairs, how do I get the check engine light to go out.
                          Thanks a million, Wayne Shumaker

Answer
hey there. if the fans are running all the time, then that is an obviouse problem. it is possible that the coolant temp sensor is faulty which keps the fan on all the time, that is "limp" mode for the fans. Is this a clutch fan? or electric fans? the coolant temp sensor is usualy located close to the thermostat housing, if not the directly on the housing..
Chris