My car would not complete catalyst monitor and I discovered using AutoEnginuity software that one of my lower O2 sensors was erratic.
My first thought was to just swap O2 sensors bank to bank to confirm.
So I spent considerable time and effort to just remove the lower passenger O2 sensor. I reviewed several threads with suggestions to no avail. I finally used a pickle bar with a five pound sledge and offset socket to loosen that sensor. Checked the other side and there was no way to get to it.
I then pursued just removing that sensor and discovered that the connector ends up against the firewall and I had to remove the throttle body and a big electrical junction box to get to it.


At this time I decided to replace all four and do it by the book. Which turned out to be fairly simple and less time consuming than expected.Removal
1. park car on ramp with front lifted.
2. remove the two engine coverings, air tube, and throttle body and move the coolant reservoir to get access to catalytic mounting nuts, remove all 8 nuts, 4 each converter to exhaust manifold
3. remove nut holding junction box to support frame and move junction box out of way.


4. release four O2 sensor connectors from junction box support, and then disconnect sensors and move sensor leads to catalytic converters
5. loosen four muffler clamps and move front muffler forward to release from intermediate mufflers, I used big rubber mallet and banged against the middle braces of front muffler
6. once middle mufflers are disconnected, move front muffler rearwards and remove from car
7. remove 2 bolts each side holding catalytic converters in place, and lower converters and move to work bench
8. remove and replace sensors

Installation
9. using new exhaust gaskets, place converters back into position using 2 bolts each at bottom support, do not tighten those 2 bolts, leave a gap between converters and bracket to give you some play when mounting the mufflers



10. snake the connectors up to firewall area, I used a string to pull them up, and connect to correct receptacles and mount receptacles in place, reposition junction box and secure in place with nut
11. reinstall throttle body with new gasket
12. reinstall forward muffler, do not tighten clamps
13. install and tighten catalytic converter nuts to exhaust manifold, ~22NM
14. tighten 4 bolts to secure bases of converters, ~45 NM
15. tighten 4 muffler clamps, ~70 NM
16. reposition coolant reservoir and secure with bolt
17. reinstall air tube, and engine coverings

 

I always recommend replacing the catalyst studs and nuts.

 

good recommendation
I did replace my studs, about $5 each from internet Jaguar dealers. I have some copper nuts somewhere in my pile of stuff.

 

Well done....