This started the other day. Got a 0150 code. In watching my UG, the Front O2's are almost identical readings at start up. after about 20 seconds the front passenger O2 drops to 0.000 and trips pending code. As soon as I start to drive, it comes back to life and seems ok, the fuel loop is closed. After car gets up to full operating temp, it goes off and on to an open fuel loop and the front passenger O2 eventually goes to reading 0.000 again.
swapped out that O2 does the same thing.
I have run as much of the harness as I can without taking IM off looking for exposed wiring. One thing I have noticed is that two of the harness wires go into a covering that has wire inside that appears to be some type of shielding? A friend who is a good wrench turner ran a continuity test and noticed that the wiring in the shielding would make his tester buzz.
This is really driving me nuts and if anyone has any thoughts I would welcome their opinion.BTW, drive side O2 is functioning normally.
Not in a position to turn this over an LR mech ( indie or stealership)right now, so all help really welcome.

 

I did a writeup in 2011 or so on a D1 O2 issues

http://jeffreyfall.com/landrover

Might be useful.

I just buy O2's off of Amazon for around $57.
Make sure they are Bosch.

And you can just unplug the huge square plug and get them on that way.
The trouble is getting the huge plug detached from the frame.


You gotta reach way up there.
And have the patience of a Saint.

 

Jfall-
I have been buying them off Amazon. High failure rate. When I spoke to a amazon rep last week, they told me they are thinking of pulling the Bosch off, too many returns.
I have gotten the big plug off the tabs, passenger side from top, driver from bottom. A true PITA!
I did read your write up, thanks. I understand what you are saying, but my passenger O2 is doing the opposite of what you describe. It starts at .445 goes down to 0.000 comes back to life, and then as the engine reaches normal operating temperature 188*, it just fades out to 0.000 again.
In some instances, the UG will pop a pending code when i turn the key to position 2.
My big question is about the wiring. two wires go into a larger wire that appears to have shielding. I think this is where my issue lies. I am trying to avoid pulling the IM and tracking the wires or a trip to the mechanic.

 

i can tell you exactly how the wires are routed if you want to trace them. they converge behind the intake manifold, back by the coils, and into the T fitting in the engine harness. from there they go to the passenger side and strait down to the computer. getting the harness apart and identifying the wires actually wasn't that bad. it sounds like you have a sensor issue since it is fading slowing and not just dropping to zero immediately

 

Front O2's will oscillate from .1 to .9 volts. If they are NOT doing that then you are in trouble.

Back O2's will go from 0 to .445 or so.
Back O2's only rise in voltage when the engine is really working and the converter is having to burn a lot of gas up. Like you are going up a hill.

If you have a bad head gasket which is just leaking and not even bad yet,
but leaking near the water jacket you will get antifreeze into the exhaust and ruin the sensors after a few weeks and a month or so.

If every two weeks you are adding a pint of coolant then you have head gasket failure on the way - MAYBE.

Put in Barr's leaks to buy yourself time and not eat up the new O2's.

 

So to close out this thread. Jfall, no coolant leak at this time. KingKoopa thanks for the wiring routing.'
It turned out to be another bad sensor. I was very concerned about the wiring being an issue as the O2 sensor was not even 3 months old. After a long conversation with Doug at AB, he also thought sensor. It is interesting to note that the OE sensors are Bosch, I am guessing that they are made in Germany not here and then shipped to the UK. In the UK, Walker O2 sensors are the replacements when OE go out. I bought a pair of Walker's from AB which are approximately the same price at the Bosch from Amazon.
Only time will tell, but I suspect the US Bosch sensors do not enjoy the same level of quality control as do the German ones.