Blue Slug

I had the same. It's on the gearbox, and changing it cured the issue.

" The car does not get up to temperature on the dash yet heating warm etc. Replaced the thermostat and the engine temperature coolant sensor yet no change on the dash. Sensor was a branded sensor from euros so not expecting it to be duff but I am here for advice. " I had this on my 56 plate 2.2D sport. Had it for 18 months and 25K miles. Gauge would fluctuate from less than 1/4 to almost 1/2 way on a journey, as conditions changed and engine was worked harder or easier. I read elsewhere that the oil thermostat on this engine could be the source of the problem. While getting other work done I had it changed. The temperature dial now sticks much closer to the 1/2 way mark, but still moves around a little and never quite hits 1/2 way. MPG seems to have increased by 1 or 2 mpg, but that could also be down to other service work. Hope this helps.