I've about worn this subject out, but thought I would add one more comment.

Yesterday I swapped car's and started driving the 05 XJ8L again (the one giving me the codes)

Today I did what I last posted, to see if it would work (do a hard reset)
Much to my likeness it did in fact work--at least for today. After the reset, I drove the car maybe 40 miles and stopped and started twice--no codes.

So those of you who have stated the same problem, but have not been able to find any air or vac. leaks, you might try the hard reset and see if it works.

I just hope it last.

PS: Thanks again DON B.

 

I did the hard reset for about 10 minutes only.
Hope it keeps working.

 

It clears the fuel trims etc so if you have any leaks it just takes time for it to relearn that they exist and as they are 2-trip codes to flag them.

If they do re-flag, watch fuel trims to confirm and if so go leak hunting (again, if you've had a go).

 

Thanks JagV8, I had that feeling, so will see what happens in the next few days.

Cheers

 

I have had those codes on other cars. They never go away by themselves even after a reset. The reason was always a leak from some hose or another in the manifold.