what do you plan to do with a scope ?
Judging by your first post, do you think it plugs in the DLC ?
EOBD compliency is usually 2001> for petrol & 2004> for diesel.
If you haven't already get a scan done of the PCM (Citroen specific) & see what DTC's are there & relevant, clear & re-scan after the fault occurs.
One piece of advice, unless you're trained don't touch the HP side of the fuel system !