At a glance
What can fail
The passenger airbag sensor may fail to detect an occupied seat, causing the airbag to deactivate when someone is sitting there. A yellow airbag warning light appears on the dashboard.
What the fix does
Audi will mail you instructions to visit a dealership, where technicians will replace the passenger seat sensor control module.
Summarized — see the official notice for exact wording, dates, and contacts.