Martin
In a nut shell NO. Still working on it but I will get to the bottom of it. I shall tell the world what the problem was once I have solved the puzzle. Have just invested in a full blown Jaguar diagnostic and computer, the IDS/SDD that Jaguar agents use. Am now in the process of attempting to learn how to use it. It does not seem very easy or straight forward. However for a 71 years young non computer brained petrol head, it was never going to be easy. I now have my son in law on the trail of of exploring the route to using it correctly and he is a bit of a computer technic who usually has success with sorting any computer that I manage to almost destroy. The other problem is I am not engineering competent on todays electronic mechanics as I was brought up on, in my early years of mechanics, on a Mk 2 Jaguar with no fancy electronics.
The most advanced I ever maintained were my Nissan 200SX`s and my Nissan Skyline.
Good luck with P0420 and please let me know if you find a resolve before I do.
Nest Wishes and Regards, John