Eliminate Precat

[proteusx301]

Ok, I've searched for quite a bit, and maybe i just havent seen what i need, or maybe im just confused. I can't seem to get a straight answer out of any post. Will eliminating the pre-cat throw a code? Im planning to use either a OBX short header, or Kamakazi short header, and keep the main cat. I need to know if the check engine light will stay off with at least one of the cats in the system. Apologies if im being amazingly ignorant.

[Danger DANJ]

Yes, you will throw a code. The O2 sensors are before and after the pre-cat, so if you take it out, both O2 sensors will read the same and cause you to throw a code. If you were to move the O2 sensors so they were before and after the main cat, you should be fine. Or you'll have to get an MIL eliminator.

[proteusx301]

what if i run a sim on one of those sensors?

[pinoyesv6]

if the sim does its job then you won't throw a light. the sim is absolutely pointless if it doesn't do its job

[SpaceGhost711]

I installed a OBX Short Header on my I4 and moved all the cats. I relocated the O2 sensor and placed it in the header instead of under the car. That solved 2 issues:
1. Got better response from my O2 sensor.
2. Quit throwing codes.
Moving the O2 sensor farther away from the rear made enough difference so the computer thinks the cat is working. Mine is a FED Spec so I don't if it would work the same on a Cali spec?
Hope this helps.