If the unfortunate situation arises that a driver has added AdBlue in the diesel tank. Do not start the engine as this will circulate the fluid around the vehicle’s fuel system. AdBlue is not compatible with many metals and materials that make up the internals of the fuel system. This including cast iron, steel, brass, aluminum and zinc, so it can corrode the pipework and components. This can cost thousands of pound worth of damage, not to mention the loss of use of the vehicle until the tank is drained and all repairs have been carried out. You need to get a professional to drain the tank and flush out the system before starting the vehicle.