My engine cut out 3 times while driving at 90mph. Scary stuff. The garage has siad it may be a problem with the immobiliser CPU. Has anyone else expericed this? Is it a common S2 issue? Any thoughts would be good as it sound like it may be expensive

 

Is the green key light flashing when the car shuts off?

If it is not the immobilizer system is not at fault.

 

Slow, it is even active after the car starts? I swapped keys/lock from 02 to 04 and after the car started, I could remove the AP1 key and the car would still run. Maybe for safety reasons, once the car starts, the system is disabled?? just a thought

 

I think you need to find a new shop.

You need to describe the symptoms in more detail before anyone can even guess. Codes, condition of the vehicle, mods and all that.

 

It shouldn't be active when the car is currently running. Some immobi receivers have been known to bug out. It's quite rare.