2006 Audi A8 Quattro Recalls
The vehicle requires a certain amount of battery voltage to operate all of its electrical components. The air bag warning light and passenger side air bag off notification light may both come on if the battery is slightly weak and allows the voltage level to get too low. This would keep the front passenger side air bag from deploying in an accident.
The front passenger air bag may not deploy. The air bag warning light and the "passenger air bag off" message would appear, causing the air bag not to deploy in a frontal crash.