this is something a dealer guy shold look at it. it can either be a short from coolant temp not reaching dash, a ecm failure, a dash failure or a short circuit in harness to instrument gauges or from ecm . not much you can do on this one without a pro type scanner to find the actual part where it is screwed up . It could also be somehting like the ecm needs reprogramming

Thank you, sir but I will have to drive it 2 hours to a dealer and they let us come home with it in limp mode because they said the part was no longer made. we bought the part at Jaguar Heaven in Stockton CA , used fuel sensor module..
$450 and also husband put in 2 new fuel pumps; reconnected all: Stared drove to a friends across town (small) and the limp mode code came on!
Only a dealer can do it? My husband does know how to check all the fuses and connections in the modules. He put in the 2 new fuel pumps (lots of cussing). We have the Electrical Manual for 2000 - 2001 xjr (153 pages) and the 1998 - 2003 Electrical Guides and the Chilton European service manuals for 2004 and the european repair manuals for 2005 (includes xjr)...He can usually fix anything but not computers!

Thanks for your time, I am going outside to see if he wants to ask/say anything to you..he gets frustrated easily with the British design and language! Also the codes are on 4 different lists and its hard to cross reference them when we do not speak British! (Love the language but have to learn it) I just got bonnet down and generator!
Thanks Susan Heringer

i don't blame you , but this can be something more than a module if a ecm/pcm is bad it has to be replaced and reprogrammed if he can check the coolant to dash circuits as well as the other things i've mentioned then you can track it down to maybe the ecm. if it is try a junkyard or something similar. BTW earth is ground for British and also bonnet is hood generator -alternator etc. lol.