I know this is a common fault with these cars and that the usual cause of the problem are the connectors below the front seats. The first time the airbag light came on a fiddle with the wires under the front seat sorted it.
The airbag light came on again recently …… soon after adjusting the front seats!…… so did some research on the forums to find a better fix.
A popular fix is to remove the connectors totally and hard wire the joint but another option from a well respected forum member suggested repeatedly connecting and disconnecting the plug then filling it with vaseline. That seemed a better option.
Definitely disconnect the battery and leave for half an hour before starting the job. The plug comes apart with a bit of jiggling if not a small screwdriver to release the tab (see arrow). Did as per instructions by connecting and disconnecting the plug several times then pushed a dab of vaseline onto the female end of the pins and pushed the plug together again.
Job done and all seems OK ……. but early days!