Got abit of an update,
Took it back to the dealers last friday with the warranty,
Just to scan the car and see why the engine management light was on, they that one of the catalyic convertors has gone,
There saying it could be the heat insulation thats cracked or something, so they are having the car next week for a day to sort it out.
They have been pretty good so far as far as the nissan dealer goes.