Okay, first of all apologies for the delayed post back, was waiting til all affairs had been settled.

After sending the unit to a certain company for checking, the 'gentleman' explained that the cost for bench-testing was $x, and that for an additional $y he would be able to reprogram the units mastercode so as it would not require the Subaru mastercode anymore....i said i would wait to see the results of the bench-testing first...was then contacted again where it was confirmed the module was faulty, and the cost of a new module was $z, so i decided that this was quite unreasonable for an alarm system that has proven it is indeed quite useless in my opinion (it has only lasted 4-5 years & less than 50,000kms), so i told him i would prefer just to pay him $x for the bench-testing and have him return the unit and leave it at that. He then argued that i had to still pay him the extra $y for the reprogramming of the mastercode, which i didn't even want (as i had decided that for the cost of a replacement module i would install a more reliable alarm system) and which had been offered as an extra cost NOT a required cost to perform the bench testing...long story short he charged me the whole $x + y, the transaction receipt and invoice arrived promptly in the post 2 days later...but no module....it took a rather heated email explaining that seeing as he has charged me this extra money i would like my reprogrammed module back so as to at least be able to drive the car to have the faulty system removed...it took nearly a week for the module to arrive...the car is now having a much better more reliable alarm system fitted

So recap, the engine light was related to the immobiliser system, even though it shows up as an error related to the fuel control unit, if you encounter the same problem, replace immobiliser with better product and forget all the messing around with Subaru and factory alarm company