Alright so I'm new to the Audi world so far I'm liking it a lot. I picked up an 02 A6 2.7T two weeks ago. It had 101,000 on it and I paid $9200 for it. I think I got a good deal. I paid an extra $995 for a 5 year 100,000 mile warranty.

Anywho I bought the car witht the check engine light on. Its throwing a code for the cats basically telling the second o2 sensor that the air isn't clean enough. I forgot to ask the dealer what the actual code was, but I'm heading back there on Thursday to get my oil changed, and a couple other things they agreed to fix.

Now to my question could this cat problem cause any problems as far as loss of power or mpg's? The car runs like a top now, but obviously I've never driven it without the cat problem fixed so for all I know it runs like crap compared to what it could run like.

Just a second quick question. The dealer said it doesn't matter what kind of gas I use in it, however the manual says no less then 91 octane. What are you guys thoughts on this and what do you pump in you cars?

 

gas only really matters if it starts to knock, then get higher octane - this is the 'ole Cadillac rule because they say they need premium but of course it's not that bad on the engine either way.

 

I always use premium 91 or 93 whatever is available, dont worry about those pesky secondary O2 sensors, they wont cause any further trouble, they are only meant to measure cat efficiency, in fact I coded mine out and went catless