Originally Posted by Mark M

The front stays at normal height. I'm so frustrated with this air system

Originally Posted by wfooshee

I was, too, with mine. Threw in the towel, bought a set of Arnott coilovers, and couldn't be happier!

I've become a total non-fan of air suspension systems. Manufacturers sell them for primo comfort, and when the car is new, they're awesome. What no car salesman will ever tell you is that the system is junk within a decade. Compressors die, the desiccant saturates and allows water into the system. The fittings leak. The struts leak. Who knows what those valves look like if they've been wet? It's simply too complicated, any water in the system starts destroying the moving parts and the seals, and it's simply not possible long-term to keep water out of the system.

I will never buy another car equipped with air suspension, or if I do, I will allow $$$ for the replacement with the steel springs God always intended for cars to have!

Originally Posted by Don B

Off the top of my head, it would take a very particular combination of valve positions in the valve block, and the compressor exhaust valve opening, for air to escape from the rear air springs and not the front air springs.

It doesn't seem like it could be a ride-height sensor issue since both rear corners have their own sensors and both would have to be telling the ASM that the suspension was too high for the ASM to intentionally lower the rear.

If you haven't done so already, the post at the link below is worth studying, along with the documents it links to (a few of the links are now dead but I think the most important ones are still good). It will help you understand the system and its operation.

Air Suspension & ECATS System Summary: Components & Operation

Cheers,

Don

Originally Posted by ChrisMills

Just a point which might not have been mentioned.
Assume you parked and locked your car with all the air pumped up. Then suspension goes down overnight. Merely unlocking the car (no engine, no compressor) should pump the suspension up from the reservoir near the valve block. It only has the capacity to do this once.

If it doesn't, I would opine that the reservoir is not holding air (obviously!), and I can only imagine the associated reservoir valve is leaking. Or something (just to cover myself). So other valves might be leaking too.
(sometimes my shocks go down, but my reservoir never does in weeks and unlocking will pump it up. Which is why I don't like opening my hangar-queen unnecessarily)

I don't see too many suspicions placed on the valve block, but air valves holding air "long term" (or overnight!) strikes me as a weak point. It's not a NASA cleanroom, a bit of dust through a not-so-good filter and you're stuffed, I imagine.

Also, the compressor should run with the engine started and the car not moved. Not sure of the delay until this happens. If it doesn't, not sure how to tell if there's an electronics fault. My hoofy method would be a battery disconnect fancily known as a cold reset.

Originally Posted by Don B

Since your scan tool can read the Chassis (C-prefix) codes, are there any other codes at all stored, such as any Network (U-prefix) or Body (B-prefix) codes? Any additional clues would be helpful.

It would probably be less expensive to purchase the parts for one or two gauge setups like lcmjaguar's than to purchase a new or salvaged valve block assembly. The gauges are very handy in helping to locate leaks.

Originally Posted by ChrisMills

I note that Don says "Sometimes the ASM will not start the compressor if fault codes are stored".
C2302 = "Mechanical / pneumatic fault such as:– pipe disconnected – air leak".
Don also suggested wiggling connectors, always worthwhile with electronics.
I understand ride height sensors would give different codes.

Looks like an air leak. If you've replaced all corners, compressor, soapy water, what else is there? It's just that I don't recall people replacing the valve block too often. But then, all those who went to coils didn't finish the diagnosis.

Originally Posted by Mark M

Thank you for your reply, well upon walking up to my car earlier today the rear end was on the floor having not been used since the previous day as is always the case at the moment, however unusually this time when I unlocked the car the reservoir tank immediately lifted the rear end up taking it just out of the too low zone, it was still sitting lower than it should and the rest of the raising was done with the comthessor which only cut in at plus 25mph despite waiting 5mins with engine idling first. I'll see if changing the valve block makes any difference next as I can't find any obvious air leaks anywhere using soapy water. I'll also try wiggling connectors and rechecking air lines as far as I can. I do really want to be able to resolve the air system problems having spent so much on it now.

Kind regards

Mark