I have tried for two months to get my 01 chevy cavalier to pass an emmissions test. Every time it comes back OBD NOT READY. Specifically the Fuel Sys, Comp, and 02 sensor read NOT READY. I have driven the car about 50 miles today and tried the emmissions test twice, both with the same result. Every time I've tried the test it has been burning natural gas. There are no check engine lights on or anything abnormal, and the car runs perfectly fine in both natural gas and regular gas. Any ideas how I can get this car to pass an emissions test. It's obviously a problem with the car's self testing system.