A6 - Computer Code P0432 - Main catalyst?
 

I have a 1999 A6 Avant quattro. I have a check engine lighton and just got the following computer code from my freinds diagnostic readed: code is P0432 - Main catalyst below threshold (bank2).

Does this mean the catalytic converter is bad or just a sensor? Are their 2 catylitic converters on this model? What does bank 2 mean? How do you determine which converter is bad if their are 2 of them?

Please advise.