Hey,
I just wanted to share what issue I have experienced with my cat and what was the solutions. Maybe this can help someone.
I was driving from Luton Airport to home when my car showed in the dash restricted performance icon. Car went into limp mode. As it was late and no garages were open I went home. Next day no error in the dash car behaved normally. I've put the diagnostic and found P006A-00 DTC ( Manifold absolute pressure-Mass or volume air flow correlation). Went to garage to check what can it be and after striping the engine they found that the passenger side inlet manifold was cracked and it was loosing pressure. I've called Jaguar dealer and asked for part price and quote for repairs. The price part is 275£ inc VAT labour 620£. So I've decided to went to another local garage and the labour price was 320£. I've chosen the cheaper option.Everything is sorted now and the car performs normally. There may be other issues under this DTC not necessarily the inlet manifold but if it ever happens (hopefully not) you make take this into consideration. Car is 2010 Jaguar XJL 2010 3.0D 115000 miles.
Hope this is helpful!

Cheers