[Standup303]

Just got my cars emissions done here in CO this morning. They didn’t look under the car and just did the ODB sensor from what I could tell. Would I be able to pass with long tube headers and high flow cats? I wouldn’t mind if I just had to load in an emissions tune every 2 years to pass then pull it right out. But definitely don’t want to be swapping cats in and out.

[bishopts]

I feel like this has been answered a lot here.

If you remove the emissions codes before you do any of the work then you should be good. If you wait then you're gonna end up having permanent codes that will never clear.

What i did was switch all of my emissions codes and non essential codes to "no mil" or "dont report", depending on if they would be useful for future diagnostics.
It ends up leaving more important codes able to turn the engine light on and non essential ones able to leave a code to diagnose from without setting a visual check engine light. The dont report ones need to be for emissions components that you don't want them to do anything. When you're done your readyness monitors will mostly be set to ready pretty much instantly. If you're state is like ours then you will be able to have 1 not ready and still pass

[Standup303]

Great thank you. Im going to hopefully chat with the local tuner I’m planning on using this week and see what he typically does.

[m6-lt1]

Originally Posted by bishopts

I feel like this has been answered a lot here.

If you remove the emissions codes before you do any of the work then you should be good. If you wait then you're gonna end up having permanent codes that will never clear.

What i did was switch all of my emissions codes and non essential codes to "no mil" or "dont report", depending on if they would be useful for future diagnostics.
It ends up leaving more important codes able to turn the engine light on and non essential ones able to leave a code to diagnose from without setting a visual check engine light. The dont report ones need to be for emissions components that you don't want them to do anything. When you're done your readyness monitors will mostly be set to ready pretty much instantly. If you're state is like ours then you will be able to have 1 not ready and still pass

No one has explained this as well as you did. I always wanted to know if the monitors would be set to “ready” or not.