peugeot expert van?

Hello,does anyone know how to bypass the immobiliser on an 03 expert van 1.9d non turbo dw8 engine.i have fitted a new engine but have left the battery disconnected for about 6mths and now the red light on the dash won't come on(or off)and i cant get fuel to the injectors although its at the pump ok,all i can assume is the immobiliser...unless anyone has other ideas???but how to bypass it will be a great help,thanks.