Heres the story. Recently I was getting the P0420 & P0430 CEL due to my High flow cats, so I decided to get O2 extentions and install them.
Now that Ive installed the Oxygen sensor extentions Im getting P0056 & P0161 Error codes. I looked up the codes and they both seem to be related to post cat Sensor on Bank 2. I have 2 questions;
1-Which is bank 2?
2-Did I break that sensor? SHould I order a new one?
*EDIT*: Sorry guys in the tittle I stated error code P0121, but the actual error code is P0161. It was a Type O, sorry :)