I have a tricky question. I know that if you take your cats off it will pull a trouble code and can cause you to fail emissions and if you put on 02 simmulaters it lies to the computer and no codes come up therefore you pass. Can you build your car emmisions illegal and still pass emissions if you have your computer programmed to not reconize the codes or will the test seek it out and find what you are running? could you still use o2 simms and lie your way out of it. I base this question on OBD2 testing

 

You will fail if any of the emissions equipment is disabled in the PCM. The new plug-n-play OBD2 emissions testing is just that, they dont actually sniff it, just rely on your rear O2's. Sims work just fine.

 

So if i put in a cam and it totally made it illegal I could pass if I stuck simms on there. And how do i get a pic of my car on here like you did?

 

can I have it programmed were the codes are there but they just show any trouble or can they only be erased

 

For the pic you have to get an "avatar", there are instruction somewhere on this board, check user cp.
For OBD2 testing, I actually found the proceedure online, they rely on your PCM for all emissions data. It must be there though, it is logged in the memory so clearing the codes, unplugging prior to testing, programming things out just wont work. This data is logged durring a driving cycle. The only thing they start the car for is to visually check the SES light to make sure its off.