The one on mine is built in to the cooling system and is a sealed unit so you have to replace the entire sealed unit, hence the cost. The changing also loses cooling fluid so the antifreeze needs to be topped up, then I was at main dealer prices plus VAT. Altogether not a cheap replacement. Other hints for potential or current 2009 2.0 HDi owners:- The windscreen trim can fly off at speed, this was a recall on early 2009 models and should have been done. There is a recall on late 2009 models for a defective wiper motor which may cause a fire. There was a batch of short wiring harnesses which cause a bad connection on the footbrake switch, this manifests itself as random unexplainable defects, none of which you would expect to come from this fault (including limp mode). Citroen know about it and have produced a short extension piece which fixes the problem but they have not recalled affected cars and only do the work if you complain enough or have a good main dealer. There was also a batch of faulty engine bay fuse boxes which can cause the autobox to fail to select the correct gear.(Mine only gave me third) again Citroen are aware and again they have not bothered to do a recall. My car is now out of warranty due to mileage so I have fitted K&N filters and chipped it to 180 bhp which makes it altogether a better car to drive, Still doing 42mpg with high speed motorway use, can get 46 if I drive like an old man (I am only 60) not bad for a fully laden automatic. I previously had the Avensis 2.2 deisel which I chipped to 200 bhp but it didn't like being so highly tuned so I dropped it to 180 and then it gave me 50mpg which I put down to being a manual gearbox. Don't believe the Toyota Hype, it had more problems than the C5 has.