So I'm at the point of tracking down a "bank 1 lean" condition and my conclusion is (for now) it's the passenger (US) oxygen sensor (smoke tests are coming up fine, and live value monitoring is not pointing to a specific issue, and the injectors and seals and all intake manifold gaskets are about a year old).

I thought getting the sensor loose was going to be the issue, but with one of the tight-space O2 adaptors (Atlantic British has a youtub on them and sells them) I had the sensor free in about 5 minutes, 4.5 minutes of which was me figuring out which ratchets would fit.

But I'm stuck on the connector... there's just no slack and I cannot put enough thumb pressure on the connector to release it. Is there a trick to getting these free or getting more wire harness slack? There's so little room and of course I can't see anything in there to know if there's a 'pop out' wire harness grommet in play.

If I can't get slack I'll try pulling the transmission heat shield to get a bit more room for some pliers... but any suggestions welcome. Of course I have 12 hours before a snow storm....

 

Ok, done. That was not a fun job. So here's how I got it done:

There's very little room from down below (Land Rover, would it killed you to have given an extra inch of wire harness slack?), and if the connectors were fresh or someone has very strong hands, you could probably undo the connector one-handed. I could not. There is, however, more room up top. I dropped a wire down from above the exhaust pipe, tied it to the old sensor, and then pulled the sensor up into the top of the engine bay. Then I examined the new sensor connector and determined that there's an "inner plastic hook" in the connector on the car that I could use a pick to get at from the front, and that's exactly what I did. I attached vice grips to the sensor part of the connector for grip and within 30 seconds with a straight pick I had the connector free. Attached is a picture so folks can visualize it better.

As for reconnecting the new sensor once it's installed, things got a lot easier when I realized that there is room for both arms to reach into the bottom, one from by the transmission and your other arm can reach up through the engine bay opening in the frame. I could not reconnect the sensor with one hand... with two hands once I realized there was room, I had it connected in 30 seconds.

So... this is not a fun job with some basic pitfalls that can take what should be a 30 minute job and make it a multi-hour job if you're unlucky. Here's a picture of the setup I used to free the connector in case it's helpful to anyone.
- scooter

 

Ok, more insights. I did not have the connector properly seated the first time, so before yesterday's storm I went under the car again, undid and cleaned the connectors. This time, knowing what I was doing, I was able to easily free the connector with one hand with a short straight pick to lift up the tab from inside as I had done before, holding both the pick and the O2 harness / half the connector in the same hand. So, this job is doable from below.

 

Great job on figuring it out and getting the connector cleaned and properly seated!