Hi All, I have a 2005 2lt tdci Mondeo and i have  had issues with my temp gauge reading for several months sometimes it will not rise above 60c and sometimes it will rise to 1/2 way another time it will fluctuate between the 2 quite dramatically. Last week I suffered a severe lack of power (limp mode?)  and notice that the temp gauge  was reading Zero as if the ignition had been turned off ...when I stopped the car switched off then restarted the car everything was normal again the gauge read normal and power restored ...however 1/2 hr later it done exactly the same again , and once again by stopping then restarting cured the problem BTW I had no warning lights . After reading some forums I noted that the possible cause was the cylinder head temp sensor which I have changed ..So far the problem has not re-occurred , however i still have the same problem with a erratic temp gauge .My question is , what does the cylinder head sensor control , are there any other sensors which could be causing the gauge to behave erratically or could it be a thermostat issue, I have been told there are 2 ..any help would be appreciated   Thanks

this is a common problem on the mondeo, there are two thermostats and the second one which is called the oil cooler thermostat plays up and causes the temp gauge issues (moving up and down when travelling) there are plenty of posts on the web and guides to changing this component which should solve the problem.