2007 1.9 check injector

[pneilly]

hi, guys and girls, my megane recently has been showing the check injector and service indicator,it is going a bit lumpy when this happens but then goes fine, n smoke or real loss of power,also when this happens the temp gauge drops to zero and the fan cuts in, now I have resd your views on glow plugs and am gonna change them when I get them.plugged the car in at my friends in ford,senior tech and it came up p0115 coolant sensor, im guessing that would justify the gauge dropping but would that do the injection warning too and service light.also as I can tinker about it myself were exactly is it in engine bay. car has 157000 miles and is sweet as a nut otherwise serviced reg.

please help people, cheers Paul