HELP lol my 406 hdi wont start all i get is imobiliser fault message i have tryed both keys all other things work it turns over just wont start i have cleand and checked all earth connections ect and made sure ther is no damp in the ecu n module and am now realy stuck

Is there a battery in the imobilizer? if so is it flat. (a problem that occassionally occurs in Saabs)

I had a problem with a renault where if the car battery was low the imobiliser would prevent it starting. Putting a charger on started it straight away.
Its an easy one to try?