what car is it, mk4? i thought these had the immobiliser built into the dash, or is that only on later models...
either way plug it into vag-com and it will tell you if the immob is kicking in and why. you dont need to change the reader coil btw, this isnt matched to anything. the chip is coded to the immobiliser box/clocks, then this matched pair is coded to the ecu.
you dont need to touch the chip or immob box/clocks either, all you need to do is change the ecu then code it to the immob unit/clocks with vag-com