Got my Expedition smogged. 9% O2 in exhaust?
 

This was a bit mind-blowing. I had my Expedition smog-checked last week. The tech guy was surprised at how clean the exhaust was. This doesn't make any sense... 9% O2, 1 ppm HC and 0 ppm CO. While I promise not to try it, exhaust is actually capable of sustaining life if you had to breath it. Well, the CO2 would get to you after a while, but the engine has to be running way, way lean. What do you think, guys? O2 sensor? Or is this normal? That engine has got to be pushing a lot of extra air through it robbing me of that boat-pulling power I need to get over the Grapevine.

pretty normal. modern personal vehicles are really really clean when it comes to exhaust, it's the commercial traffic that makes the majority of pollution these days.