I was just reading my copy of the 2003.5 Technical Notes, and in an obscure paragraph on the CATS system read that the system is part of the control software for the suspension, and if any fault condition affects the suspension, the shocks will revert to the 'Hard' setting. A dealer had told me this shortly after I bought the car when my compressor needed replacement and I had a suspension fault message. I noticed the ride had gone hard and was told why, but here it is in black and white.

CATS gets a load of info on the CAN bus on parameters that could influence the shocks settings.

 

That might explain why some folks have reported that their suspensions were much too stiff after replacing air shocks; perhaps there is still a suspension code set that was not erased. Very interesting.

I get an air suspension fault message 50% of the time, but In my case it would only affect the rear shocks since the fronts are Arnotts without the CATS damping. Hope the new i930 that is on the way will tell me which of the 35 or so suspension error codes is triggering that message.

 

Hello Phil! Would you be surprised if I told you your air suspension fault message could very well be your Arnott's shocks?

Take a look at this thread I started and its resolution from about 2+ years ago:

https://www.jaguarforums.com/forum/x...-c1424-104540/

 

Thanks, That's Very interesting. Looks like the operative statement is "The good sensor registered 6.2 Ohms." That should be easy to check. My Arnots are a newer version than those in the thread, but I bet the sensor coils would be the same.

My i930 is scheduled to be here tomorrow so I may be able to check the chassis codes to see if I have a similar open circuit code. The odd thing is that I can go a whole day without an air suspension fault or have it pop up 100 feet from the house, and ambient temperature does not seem to make a difference (yet).

 

It should be a value that is fairly low, less than 10 Ohms. Mine was not registering any resistance (open circuit). It is a coil (or inductor).

 

Got my i930 today and read the air suspension codes: C2303 (reservoir plausibility error) and C1830 (compressor relay circuit error)

I'll try replacing the relay first and if that doesn't eliminate the air suspension fault message I have Andy's compressor piston ring kit in the glove box.

It had three U codes about CAN timeout from ECM, missing message from ABS, and missing message from "electron air temperature control" (whatever that is) but nothing I recognized as a sensor coil failure in the Arnotts.

Anyone know the common part number of the compressor relay?