Hi , would be very grateful for some help if possible.. my Citroen xsara picasso 1.6 desire 2005 failed mot this week on airbag fault , i have had it diagnosed and the error is 'P1801 -AIRBAG IGNITER OPEN CIRCUIT) been advised it's probably the coms2000 unit that includes the squib ,mega bucks from main dealer

but reasonable from auction sites etc.
Has anyone had similar problem and were they able to resolve ? also if it is the coms unit how can i access it to find the correct part number for car ?
Many thanks