Audi Repair: Audi A6 Catalytic Converter or MIL problem, malfunction indicator light, proximity sensors

Question
The Malfunction Indicator Light on my 2002 Audi A6 (86K miles) was diagnosed by the Audi service dept. as indicating a bad right side catalytic converter (I wasn't given the actual codes). However, several days later the MIL went off (while underway) and hasn't re-engaged. I confirmed that the MIL is still functioning when I start the car. I've experienced no sluggish behavior, and the gas mileage is the same as always (20 mpg in town). However, with the same timing as the MIL originally coming on, I am randomly experiencing a warning tone when I put the car in reverse. It is a steady tone, and not the same tone as the reverse warning which indicates close proximity to something behind the car (steadily increasing beep). Any ideas as to what might actually need to be repaired? Thanks

Answer
Hi Linda,
Sometimes the cat can give an error for cats when poor quality gas has been used.  Also if you get the cat nice and hot on some highway driving, it can clean itself somwehat, but it is worth keeping a lookout for...  A warning tone when you put the car in reverse could be an issue with the warning system, if the tone is the same.  You might have to get the proximity sensors checked.  I do not think the two issues could be related, but then cars have strange ways to show electric fault symptoms sometimes.  Let me know, Jan