How to replace o2 sensors with cat shield installed

It would be good for you to share the actual codes rather than someone's interpretation of them.

 

If you're chasing the cat below threshold code which is PO420 I think you can change your sensors all day long if the cat can't absorb the fuel that is squished into it during the test it'll fail and be below the minimum threshold until it isn't which is one is replaced apparently now you may be able to put a O2 sensor spacer and that may adjust the signal pickup capabilities of that downstream sensor and make it not show that the cat is below threshold That's your best chance of making this happen without the expense of a factory cat which apparently is needed in this model. Ive yet to try this on my '09 Gen 2 with the PO420 code now for 3 years I've just been too lazy to crawl under the car and literally screw this thing in and screw the cat into it lock it down and clear the code and see what happens maybe I'll get to it this next week I do not have a cat shield so none of the problems usually the cat shield is put in with special bolts that you've either been provided the key for or can go to the shop that installed it and get the key from them I'm not sure how that exactly works or maybe they can make a hole in the shield so you're 02 wrench or socket can get up in there to loosen and then you can use long needle nose pliers or something to twist it the rest of the way out something here in the southeast USA cat shields aren't really a big thing so far.