Please check the FAQ at the top of the main page. There are resources for dealing with P0420

The P0420 code has been discussed quite a few times here, so you may want to use the site search function and see the troubleshooting section of the site FAQ.

While that code commonly refers to a failed catalytic converter there are other potential causes that should be explored. See the following:

https://www.walkerexhaust.com/support/tech-tips/diagnosing-catalytic-converter-p0420-code.html

https://www.carparts.com/blog/p0420-code-catalyst-system-efficiency-below-threshold-bank-1-2-2/

https://www.obd-codes.com/p0420

As far as where Bank 1 is located, that is the first bank of cylinders - the only bank of cylinders if you have an inline engine.

For some reason, your browser is generating several duplicates when you submitted your post. (You accidentally posted this topic six times.)

Are you having network issues? If so, then please wait until you have a stable connection. If you are pressing the submit button more than once, please stop. Press it once, and wait for it to finish processing. (You will find in most cases if you return to the main page that your post was processed immediately even if the submit button appeared unresponsive.) Otherwise it creates more work for moderators to clean up, and eventually the system will automatically ban your from entering.

Additionally, it appears that your post was cut off because you put your question in the wrong place, the length-limited subject line. That is intended for a short description of your topic, your question belongs in the body of your post.

Thank you. (Title edited.)