The car is a 2006 XJ8 3.5L The following messages have never appeared --> "Vehicle too low" "CATS system fault" "Air suspension fault"
The car has never dropped even after being parked up for 2 weeks The ride is smooth and quiet. Doesn't pitch or roll and corners flat.
Very (very) occasionally when crossing a sharp ridge in the road, I hear a loud bang from the Suspension (??)
I have had the opportunity to turn around and drive over the same stretch of road (up to 3 times). Result :- Nothing - smooth and quiet. Unpredictable.
Consequently I have never been able to decide whether the noise is from Front or Rear. Left or Right.
Having hunted through this and other forums for a few months, and found no similar fault descriptions, I've decided it was time to post.

Nice to be in the company of other Jaguar lovers.
Thanks Guys.

 

Where to start with that description....?
Make sure your battery in the boot is properly clamped down, the spare tyre (perhaps a space saver) is also well secured along with the jack and tyre iron in their appropriate foam storage compartment.

If it is up the front, then a common cause of stray clunks are the front sway bar bushes to the chassis, the will produce thud type knocks over judder bars and potholes. You won't necessarily see any issue with them but changing will often resolve an annoying suspension type noise.
They are fun to get to and change - not!

 

I concur with Mark and would just like to add that regarding the fault messages, you will need a Jaguar specific code reader, or, better yet, SDD, to see what is wrong. Everything else would be guesswork, and that could be expensive...

Best regards,

Thomas