What do you have to do when the Catalyst efficiency below threshold (bank 2)?

Question

I have an 1998 Audi A4 Quattro. This is what the trouble code means.

Answer 1

First make sure the downstream O2 sensor is functioning properly. Next take the car to a shop with a dyno and 5 gas analyzer and have the cat efficiency tested. This is done by taking a gas sample before and after the cat under load and seeing the % of "bad" gas reduction.

Answer 2

99% of the time you must replace the catalytic converter