One problem related to catalytic convertor has been reported for the 2001 Audi Quattro. The most recently reported issues are listed below.
I have replaced both catalytic converters on the 2001 Audi allroad. The right one at 42k miles and the left one at 62k miles. The right catalytic converter has failed again at 115k. The dealer refuses to extend any warranty for the part. The dealer states that the original part is warranted for 80k miles, but the replacement part only for 12k miles or 12 months. There must be something wrong with the car or the equipment. Audi should warranty a required federal emissions part much longer than just 12 months.