Something to check, I had problems with the airbag system on my 406 Exec - main dealer could not the cause, took me ages through a process of elimination. Tuned out to be a doggy crimp in the electrical junction strip located under the driver sea : adjust the seat the warning light lit up. It was one of the two orange wires that is linked into the seat belt tensioner system but you will have to get a diagram to track them down (Haynes manual) hope this helps
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