With the given fact that the 02 sensors are a wear item, replacing them all eliminates one item on the list.
I hated replacing mine in the 04, but mileage went up when i did.
Have yet to replace them on the 07, as they will not clear their emission part
Your allowed one not cleared, & no check engine lite on.
Just a matter of time, till they give up the ghost.
Saving up my money for all four.
One time doing a job is always my intention when i start.

 

Chris,
Did you read my post in it's entirety? At the end it was an O2 sensor issue. Some one on the forum gave me the specs for current. 0ma, -.02ma- +.02ma is normal. It almost always the upstream sensors vs downstream that cause most of the problems problems. Upstream reads and corrects, downstream just reports outcome after the cats. After changing mine, current was at .02/.03 ma and car ran perfect. Prior to that one O2 sensor was all over the place. Voltage was not the issue. And my FT's evened out within specs. I'll find my FT saga post, and link it for you. It's not necessarily the sensor @0ma's, it's the other one reading high -.39ma. The steady 0 doesn't give me a warm feeling either. https://www.jaguarforums.com/forum/x...74-sv8-177741/ #32. As many have said, change the O2 sensors. With our cars having the original sensors still in, they're about shot at our mileages. Without the correct reporting from the sensors, we really don't know at what level what exactly is going on. It's like using an uncalibrated measuring tool. ???? My sensors we about $150.00 pair. They we Denso's. Very easy to change the sensors on this car vs others.

 

thanks all.

Mark - I did read the posts on your issue but I just wanted to be sure it's the upstream O2 sensors at fault before I go and just change the parts. I've been trying to find what the correct readings should be in an attempt to try to identify that the O2 sensor is at fault. I've also been trying to work out what I should be seeing in both the upstream and downstream sensors together on a fully working system. I think I will just change them and see what happens. Really appreciate the help you've given me. Once I've changed them I'll see what results I get and report back.

 

Rock Auto has down stream Walker 02's on sale for early XJ8's for $30 each, if available to you in GB.

 

Would this Land Rover part fit a 2007 XJ8?