mk3 golf immob behaviour

[iep]

This is really an aside to my other thread but I thought it might be a useful topic in itself.

Does anyone know how the factory fit immob on a mk3 golf should work. As far as I can see, there is the reader coil on the ignition hoising that feeds to the immob in the dash. If the right key ain't there, it won't start?

If the right key is not present, what happens? Does it fully immobilise the engine (no cranking etc) or will it start and then stall seconds later?

[iep]

Just found this on another thread:

If it was the factory fitted immobiliser that would cause the car to start and immediately stop again and would not cut the car out when driving but it would leave a fault code on both the engine and immobiliser ECU's.

Anyone know if this is true? Does the immob flag up fault codes onthe ECU when activated?