Hmm, I am not sure...

I did find this on the web for you:
"What causes high CO2 (carbon dioxide)? High CO2 is the product of a good running engine. The better your engine runs, the more CO2 it produces. The only way to reduce CO2 emissions is to buy a fuel efficient car. The bigger your gas guzzler, the more CO2 it makes. "

One thing I have heard on O2 sensor trouble shooting is to unplug it; if it is faulty, it should run better unplugged...

Have you had a chance to pull the codes yet? Scott has instructions on his website for this procedure (very easy to do!):
http://www.sjmautotechnik.com/TROUBLE_SHOOTING/ecufv8.html

Hope that helps,

- Jeremy

1990 V8Q Zyclam Portland, Oregon (USA) http://www.MyV8Q.com/ Fun, Fun, Fun auf der Autobahn