Test results show the trucks had inflators that ruptured or recorded high internal pressure readings.
Inflator can separate from a plate, shooting out metal and other debris.
Japanese auto parts maker faces billions in costs for the largest auto recall in US history.
Global recall of faulty airbag inflators likely to expand to more than 100 million.
Volkswagen is recalling 850,000 Audi, VW vehicles in the US from 2006 to 2014.
Supplier Taka says there may be s many as 3 million vehicles affected.