I got my FAST a/f gauge installed, did a quickie deal since I plan to move it from car to car....

...seems to work pretty well for a basic gauge/playback device, but I have a quick question:

Will pan evac mess up the accuracy, or damage the o2 sensor?

I have the 02s a couple inches upstream of the pan evac outlets (which seems OK), but I'm pretty sure they do try to backflow under decel....otherwise, they wouldn't need check valves....