Needs plugged into Citroen Lexia diagnostic and a global scan run.
other diagnostics can read it but Lexia is the only system that can pull Citroen genuine codes.
Oh and I suspect you have a fault with the BSI,
or body systems interface.
Everything electrical runs through and is controlled by this unit.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vans.