Peugeot 806 hdi keeps cutting out and the engine management light comes onbut then the engine starts again when you turn the ignition on please help?

This happened to me on my 806 and the answer was to remove the fuel tank, remove the fuel pump from the tank and remove any debris found in and around the pump suction - there is only a small inlet port on the pump so any debris eventually ends up there and blocks the suction for the pump.Since doing that I've not had the thing stop suddenly with little warning in the middle of the road! HTH