I'm reading Bentley at:

Audi > B5 Platform > 1996 - 2002
2.8 Liter V6 5V Fuel Injection & Ignition, Engine Code(s): AHA
24 - Multiport Fuel Injection (MFI)
Heated Oxygen Sensor (HO2S) and Oxygen Sensor (O2S) control before TWC, checking

It doesn't say anything about using Basic Settings or the voltage being "Prepared and Smoothed." What manual and section did you see that in?

Nevertheless, I'll try it again tonight in Basic Settings and see if I still get voltage readings <.3 or >.7 in my samples.