you can tell if the immobiliser is working correctly by the led in the speedo,if it goes out after 2 flashes when you turn the ignition on then its fine and you may have a fuel or compression problem. if the led re-lights after a short pause then count the amount of times it flashes and this indicates a fault, you would need to speek to a peugeot dealer and tell them the fault code (number of flashes) or reply to my answer and i may be able to help you
Phil,Gosport, January 2006