Good evening Gentlemen. I have been tasked with finding out what is wrong with my sister-in-laws C3 1.4 Diesel. 2004 model. There is a strong smell of sooty exhaust in the cabin. There is a 'ticking' noise from the left end of the engine, most noticeable on idle. Although I cant see it I have the suspicion that there may be an EGR valve somewhere there that has gone faulty. Am I right and how easy is it to fix? Many thanks. Derek.