Hi Darren
Can't help specifically, and I don't know what country you're in, but, in the UK, when you open the passenger side door, I think there's a switch in the side of the instrument console plastic panel, to enable/disable the passenger airbag (for when it's not needed on for any reason). Might be worth operating that switch a few times (I think the van key can be used, or large screwdriver blade) - rain might've got in while using that side . Put it back to whatever position it started in