just erase it and see if it returns - i did 3 last week, the fault was thrown up purley because of the cold weather.

worth a try at least, its free and wont do any harm.
 
Cheers mate, Thats what i've been doing just wondered if it was something a little more worse but if its just because of cold weather then i'll keep on clearing it.
 
Under the plastic engine cover on the right hand side of the engine in the thermostat housing, its where all the pipes meet in a big plastic block, dont do it after a long run though wait until the engine is cold, if you HAVE to do it when the engine is hot undo the header tank cap first, let all the pressure out then put the cap back on then replace it - you'll still loose some coolant but you wont get hot pressurised G12 in your eyes and be very careful not to break the cheap-o plastic clip holding it in.
The faults signifying that its dead tend to be open/short circuit or no signal. The 3 that i had a look at were within 3 days of each other 1. a leon cupra diesel TDI which had the sensor fitted in september - erased it told them to give it a try and conntacted them the other day - still no light back on 2. an ibiza 1.4 auto same again the light hasnt returned and 3. was a 1.2 12v ibiza knocked the light out and all has been well. On the 3 days in question the temp was dropping to 2degrees and it doesnt take must to frighten VAG ecus, it must just be that the readin was outside its tolerance.
Its not entirely good practice to just know the lights off and send them on the way but if it stays off for another month or so then they are happy and confident that the part is buggered.