I’ve seen one on the exhaust and it’s one bit and electrical block so not a problem. I’m a heating engineer by trade but I have manuals to view parts!
That’s where I’m struggling in locating the fecker that needs swapping!
Take a look behind the resonator towards the rear of the car.
The Nox sensor is Part# 250 in the diagram below.
Don't confuse it with the Temperature sensor (Part #220)