The 2009 Audi S6 has 4 recalls, all centered on the passenger-side front airbag inflator, which can rupture and send metal fragments into the cabin, causing serious injury or death.
The underlying issue is that the propellant inside the passenger frontal airbag inflator degrades over time when exposed to prolonged heat and humidity. Once degraded, the inflator can explode with excessive force rather than deploying in a controlled way, tearing apart its metal housing and scattering sharp fragments toward anyone seated in the front of the vehicle. Prior repair attempts did not fully resolve the issue, which is why multiple recall campaigns exist for the same defect. This is a well-known problem affecting airbag inflators across many manufacturers and model years, and the 2009 S6 falls within the affected population.