hi i have a 1.7 cdti 100ps 2007 astra van sportive, when driving on the motorway at a constant speed the engine management light comes on so when i read the code it leads to an engine overboost condition, i have changed the overboost sensor and still no different and recently my turbo has gone!i now have the new turbo fitted and engine management problem still coming up with overboost sensor! anyone got any ideas as to what it could be and how i could fix it?? cheers ben