Hi all, I hoping amongst all the various knowledgeable people on here that some of you can confirm if what I'm thinking is correct of point me in the right direction. I have on my 2006 Jaguar X350 4.2ltr n/a engine lwb a C2302 levelling plausibility error which will show up normally within 3o seconds or so of the car being driven straight n level and by around 25/30mph. When this error shows up it obviously puts the yellow dash warning light on and air suspension fault message appears in display of dash. If I turn off engine and restart it goes away but comes back just as quick as explained earlier. When this fault code comes up it shows in icarsoft live data a 'damper firm error'
Ok now is the above the result of my right rear air shock leaking? This air shock will lose all its air and take the car all the way down to then produce a vehicle too low red light error on dash. Once engine started and begin driving the compressor quickly pumps it back up to correct level, and soon as I hit a straight level bit of road at 25/30mph the c2303 errors still returns.
So with all this in mind would replacing the rear shock or both rear shocks get rid of the C2302 error for good? I've already replaced front shocks last year, and air compressor last week as I think I burnt old one out and new compressor works well.
Thank you all in advance any help will be much appreciated
Mark.

 

If you have a bad leak, you'll get this code, as the system is detecting it is needing to supply more compressed air than expected, and it's having difficulty keeping the vehicle level. So if you definitely know you have a leak in one of the rear air springs, replace that one. It is not necessary to replace in pairs.

C2303 is slightly different, and normally indicates the reservoir isn't being charged quickly enough. This is either because the compressor is knackered or the air is leaking out somewhere, so the compressor can't charge it in the time defined in the software. As you have replaced the compressor, clearly it's the leak that is causing this code.

As soon as you get a suspension fault the CATS system, which varies damper settings between Hard and Soft, defaults to Hard. Soft is switched using a solenoid and valve inside the damper. This means you'll find the suspension much harder than usual.

 

That's good info Fraser. I had the same issues with my 2005 XJ8 (car too low, suspension fault). Also system began having trouble holding pressure overnight. I ended up replacing a leaking front shock last year, and a blown rear shock just recently. That fixed the leveling issue. Now I am getting the reservoir plausibility error and the consensus is that my compressor is tired, even though the shocks pump up and hold overnight. Apparently if the system takes too long to pump up it will trigger the code. I ordered the bagpipeandy rebuild kit on Ebay. Andy confirmed the kit should take care of it. Makes sense that with a leaking system the pump is working overtime which wears it out sooner.

 

The ASM software only allows the compressor to run for a fixed time, before it then shuts it off. This is to prevent heat damage, as air compressors get hot when working. The time is set to be longer than the compressor would normally take to charge the reservoir. So if the compressor is always cutting out the ASM throws a C2303, to indicate a possible leak or knackered air compressor. These WABCO compressors originally would fail quite early, in some cases within the warranty period. Wabco must have made improvements, because the 2nd compressor on my 2003 car lasted much better, and was still working when I part-exed the car. My 2007 car never gave any problems with the air suspension. Of course it suffered the usual suspenson bushes early problems like they all do.

 

As stated above, if the compressor run but the expected results aren't achieved, you'll get one of those codes. What nobody has mentioned is that the system then gives up and never runs the compressor again until the car is shut off and restarted. Once the yellow light comes on with the "Air Suspension Fault," the system won't do anything else to try to keep the system running.

 

Many thanks thats good and helpful info, really appreciate it, I ordered a pair of rear shocks which should arrive this week as I thought they had to be done in pairs, but with 110,000 miles on the clock it's probably worth doing them both, hopefully getting changed early next week.

Once again thanks all for the info everyone's chipped in with, makes this a great and extremely useful forum, i love it as there's lots of knowledge to tap in to if you're not sure yourself