Ok I've had the airbag light on for a while now as I thought it would be the connector on the bottom of my seats however it wasn't that.

It was reporting on VCDS that its the crash sensor on the drivers B-Pillar. When I took the pillar off and the seatbelt unit out and finally got access to the sensor, I was shocked to see that the sensor was corroded due to water ingress.

Now the question is if I put a new sensor in, what do I do about the water ingress. Where is it coming from as its bound to take it out again and the cushion was soaking wet, however interior carpet is dry.