Need ideas on fixing NOX related codes

Hello fellow truckers,
This is my first thread here on Volvo forum. I've been mostly active in International trucks section.
First off, Happy New Year and best of luck in this coming year.
What I want to ask you a Volvo community, since this is my first time owning Volvo trucks is help navigating\finding solution with the recent issue with what I understand is related to NOX sensor however, I'm not familiar with D13 emission stuff (mostly Navistar and Cummins)
My question comes down to this:
4 engine faults
P 221A00
P 225F00
P 22A100
P 22FE00
What's the first to check on in order to pinpoint the problem, I'm assuming it won't be as easy as replacing nox sensor.
The bad, shop cleared codes and gave me a picture of diagnostic page (see attached)
The good, I can gain access to Tech Tool software if needed.
If you can help, your thoughts and ideas are welcome. Thanks in advance

 

Thanks for heads up, I honestly hoped for what you just said. I appreciate you taking the time to reply Newto Trucking