Failed Emissions, what do these #'s mean?

[bmuser]

Ok so i failed for the second time, and its the same story.

NOx:   2572   Standard: 1134
HC:     167     Standard: 146
CO%:   0.75   Standard: 0.82
CO2%: 13.8   Standard: doesn't say
O2%:   .9      Standard: doesn't say

Ok the exhaust and cat look pretty much brand new. The previous owner said it was replaced header back to the cat. But after the cat it looks a tad bit older, but nothing rusty and ugly. So the exhaust looks fine, and im sure hte O2 sensor was replaced as well.

I changed teh spark plugs, and did an oil change. The car runs fine. Smells a little rich at times. My hoses are still old, i need to replace those,  but i taped up the cracks that would cause leaks before the test.
I also drove around for a good while and got it nice and hot.

My friend says its hte O2 sensor, that it might be possible that whoever did the exhaust reused the O2 sensor. I really hope not.

[dhirsch]

The O2 sensor and the cat are the most important parts of the exhaust system.  If you don't know how old the O2 sensor is it might be a good idea to change that.  Also, try banging on the bottom of the Cat with the handle of a screwdriver or something like that to see if it is hollow.  If it is hollow the inside has either been removed or blown out, so it's not doing it's job...

when I got my 318is the cat was shot.  I ended up welding in a magnaflow cat and it passed with flying colors, but my exhaust also looked like rusty swiss cheese

[bmuser]

dude it looks brand new, or almost. u cant fake that suff. but yea ill tap it to see if its hollow.