I have an old-school 2.0DTI in a Vauxhall Zafira. I have had issues with the EGR valve for about three years. Instead of having it replaced my local friendly garage "cleans" it and all is well, or was for about 6-8 months. The reason for cleaning was financial, £50 to clean or £450 to replace an item that may well go again in two years. I tried staying clear of supermarket fuels and going for the more expensive, cleaner ones and this helped initially but the time between cleans kept on going down. I then tried "Miller Oils Diesel power Eco Max" at a double dose strength, at this stage the warning light had been on for a week, and after about two days the light went off and has been ok now for over two months on just a single dose each time. The cost is negligible as I definitely get at least a 3 per cent improvement in mpg, which offsets the cost (one bottle treats 500 litres of diesel). This might be useful to your readers.