Hi sorry I have not replied to all the posts been away ,right I have taken the car to a diesel specialist but they could not get it to connect to a plugin scan tool but he told me of a problem that he had encountered which was to do with a Nissan truck they were having problems with the engine as it would not boost but in two gears (3-4) after some time they discovered that it was the neutral switch when in neutral the car will not boost but when in gear it will due to the switch being off but when in 3rd or 4th it was on and the engine would not boost ,as I left and on the way to another garage which I knew would have a scan tool which would read the car I climbed a hill in 4th gear the car just would not pull at all at 40 mph so I changed it to 5th and by the time I had reached the crest of the hill I was doing over 70 mph ,tried it again and it did the same in 1st and 2nd it pulled well but on listening to the car with the window down in 1st 2nd and 5th you could hear the turbo boost in 3rd and 4th nothing .On arriving at this other garage the owner had a rep selling diagnostic tools and he was confident that he would be able to read the car ,sure enough he was able to read the engine , and gear box he asked me to engage 1st neutral switch off the same in 2nd and 5th ,but 3rd and 4th it was on so its the switch on the gear box ,as I have the old box which has a good working switch on it it will be replaced and hopefully it will be back to normal .Many thanks for your help Phil.