Posted this in 2.7 forum, looking for an answer here. Keep getting error code on cold start, Insufficient Air Flow, Bank 1 and Bank 2.
I've gone through the entire system, all parts and hoses are working properly.

THE QUESTION:
Does anyone know what the computer actually monitors to determine if the airflow is sufficient or not? There is no actual sensor in the system, so it must be either cat temperature vs. time or upstream O2 sensor vs downstream O2 sensor comparison. I really don't want to start randomely replacing expensive parts.
Thanks for input.

<center><img src="http://pictureposter.audiworld.com/85119/img_0016.1.jpg"></center><p>here's a picture of the valve on my rs6... my guess is that the hose has deteriorated, like mine and isn't opening the valve...BTW its only for heating the cats faster when the car is cold...it won't affect performance. Check behind the valve covers between the engine and firewall

most often it is vacuum problem a smoke machine is very helpfull . if you have access to vagcom activate soleniod and see if you can hear valve move (put a screwdriver on it).also i have opened valve with vacuum pump and activated air pump you should fell air out exhaust. have seen 2.8 cars with pluggrd passages in head