It's impossible to say as it depends on which circuits are immobilized, but it will be either a ECU problem, no power etc or the CPS signal is not being received, bad wiring etc.

The easiest way to check is to see if the immobilizer LED is extinguishing when the ignition is on? If so then it's working, by indication at least.

That is why I asked first as it's pointless aimlessly changing sensors seen as no one would be able to tell from the initial information what was wrong!

Are all four lugs intact on the crank pulley as well?

Martin