How did you make the jump from "Driver-side Airbag Ignition Squib" to "R12/9 fault"? I can't confirm that you are chasing the right airbag here.
The usual suspect for these is the connector block under the seat - if a water bottle, jacket, etc, gets shoved underneath, and then the seat moved, it can cause physical problems at the connector. It usually results in an "open circuit" which does translate nicely to "resistance too large".
Only because you made the conx. This is his "squib" threadNot sure which thread that is but - you're the admin, up to you.