Dear customer, this failure is characteristic of problems in the suspension valve, I see that you have already checked the compressor and the ecu and that is very good but there is a valve in charge of allowing the passage of air to each of the ducts that come to suspensions and also allows air discharge.
It is the valve that I am going to attach below in the picture.
This is the valve information:
OEM part number
HTI - KF-2015-00011,
KAS - AA0104.01.0.001.120.1
(For compressors: C2C2450, C2C22825, C2C27702E, C2C27702,(###) ###-####
III.The part conforms to the following:
Land Rover for Jaguar X350
XJ; XJR; XJ8 Super V8
Vaden Plas 2004-2009
2003 - 2010