Light Flashout Code 42 is for the driver's air bag circuit. The most common problem in the clock spring or sliding contact as Ford sometimes calls it, in behind the steering wheel but it could also be the bag itself, the wiring in between the bad and the RCM ( Retsraint Control Module) or the RCM itself.
The manual lists a bunch of pinpoint tests which require some caution and knowhow so you dont accidently set off the airbag while you're testing
I would take a look at the connections under the steering column. If they are all ok you could maybe remove the clock spring and test it with an ohmmeter.