My 2006 X350 shows up an intermittent AIR SUSPENSION FAULT. It doesn't show all the time but mostly. The ride is excellent and there is no dropping of the cars' level even after a prolonged period unused e.g. 4 weeks. I am sure the problem is a faulty sensor, either the front or rear. So, my question is, is there any way to determine which one it is? Or could there be another cause? I would like to have the fault warning eliminated as it is annoying and also when the time comes to sell my car it would be much preferable for it not to be there.

 

You have 3 height sensors . One for the front on suspension arm. Two for the rear. While engine on have a seat ,carefully, at the end of the boot car would go down at first then raise after a couple of seconds. This just to test the rear height sensors. Depending on age , miles , roadcondition dust salt sand. The pivot points get dirty inside. Blow off with air then ad a drop of silicon oil..
if one is not working it should show on Sdd.
Not too expensive 90€ a piece for the front ones at Jaguar dealer Witch a more comfy ride afterwards. I used just front ones and transfered the longer sticks from the old rear ones onto 2 of the new front ones.
main problem on the compressor :
1. piston ring or cylinder marks - bagpipingandy' refurbkit. Not enough air pressure in about a certain running time ( about 14 bar)
2. Humid or even wet desiccant beads . Driable in an oven. Or new beads silica approx200ml glass full. Worth it to prevent problems in the valveblock and airstrut
3. The onlY place where exess air will be released is on the compressor as well. (Pressure release valve solenoid)

The valve block rarely gives up. If so I tend to think of the humidety in the desiccant beads going to the valveblock next . Then to the airstruts front and rear then to the tank for spare storage.
if your airstruts stay at height and level they are pretty airtight... or filled up to be leveled by spare pressure from the tank. Here cats behind the rear seat regulates height and level every half hour from the moment you switch of engine and leave the car( locked). To try if they are airtight disconnect batterie for a couple of days , so cats can not regulate height or level car. Mesure height front 386mm center cap to wheel arc ,rear 373mm rear.
or any other mesure , write them down rh front lh front . Mesure again and compare before restart.
if they drop over a couple of days you do have a leak.

 

If it comes up with a fault there will be a stored code - probably Jag specific so a better than basic reader is required. Get it read and let us know so we can narrow it down for you.

 

Yes, you MUST get a reader to get the trouble code from the Air Suspension module. Otherwise it's complete guesswork. Also be aware that once you see Air Suspension Fault on the display, the Air Suspension Controller stops working; it will not run the compressor again until the car is shut off and restarted.

 

Thank you gentlemen.
I have checked the fault with a iCarsoft diagnostic unit model LR V2.0 and it shows fault code C2303 RESERVOIR PLAUSIBLITY ERROR
Does this help? and do I still need a more comprehensive diagnostic unit to find exactually what the problem is?

 

Yes! It means the pressure in the reservoir did not reach the expected value in the expected time. In other words the compressor cannot produce enough pressure/volume to charge it. Sounds like a compressor needs rebuild or new.

 

Thank you OldKarz, So what do I need to do to access the compressor?

 

Your best bet is to download the workshop manual. It gives the method to get at it. Others will probably offer shortcuts.

 

Thanks once again, I searched older posts on this, and it seems I can access it by removing the wheel and inner guard.

 

I started the car and listened for the compressor running but could not hear anything. There was no fault displayed so I assume the system was up to full pressure. I am thinking I will still put a service kit in (the car has done 130,000 km's - 87,000 miles) I can buy a kit from Bagpipingandy UK which includes fitting instructions for $85AUS delivered to Australia. Wish me luck.

 

 

Don't just do the piston kit, go far enough into the compressor to get to the dryer chamber, with the desiccant beads. You'll find them saturated, and probably find a good bit of rust in there a well. Get all the way to the vent valve and clean it as best you can, because that vent valve is the ONLY means of allowing excess air pressure out of the system.

And consider that rust in the compressor because of water intrusion does not bode well for the rest of the system. The valve body in the trunk could be just as badly rusted. In my case, I live in Florida, obviously very high humidity, and when I opened my compressor I found the dryer chamber was actually a literal water tank. It wasn't just saturated beads, it was FULL of water. I abandoned the air at that point, ordered Arnott coilovers, and never looked back. The air on my car didn't work right when I bought it, and the rabbit hole looked pretty deep from there at the top looking down into it. I don't have air suspension, but I do have a car that I can start and drive for hundreds of miles without waiting for it to lift in the mornings, worrying about getting stranded somewhere with a "car too low" red light. Works for me 100%!

 

Thank you very much Wfooshee for the valuable info, I appreciate it and will do as you suggested. Is there any issues with accessing the dryer chamber?
Also thanks to Jaroslav Zaruba for the utube of the process, really great. I have ordered the kit and will tackle the job on arrival.

 

It's been so long since I did mine, so I don't remember what it actually took to get there. Just some more screws, I imagine.

 

Thanks wfooshee,
I have my service kit and so far so good. I am looking at replacing the dececant crystals but I have come upon this. The spring is very rusty but I don't see how to get into the cylinder/housing. Help.

 

Watch video see post#11.
The spring is not critical. It only keeps the moisture filter ***** together. Mine got so full of ***** that the spring was not necessarily.

Plaucible fault means somemfault that is happening ower time. For example if the compressor is slow but not always as sometimes it does not need to be fast. Therefore the fault might go away ned then reapere.

An answer to the initial question how to check hight sensors. A fault code analysatot like Carsoft does monitor the sensors in real time. This means that you can rock the car or eaven go driving. You can see hight information on all sensors. Do these reflect true values? Mine did first give the right values but suddenly jumped out of realistic numbers. I had the sensor wiring connector loose at the computer behind the rear seat.
So you can also seek for bad connections this way.

So it does not need to be the sensor. The sensors does not have any elektrik parts that can wear as it operates in magnet field (Hall effect sensor). But the case can break. There is an aluminium sleeve for the attachment bolt that can corrode and then crack the case so that moisture get in.

 

Thanks Spalmgre,
I guess I was not clear, I need to know how to remover the inner cover to access the crystals so I can replace them. The end cover seems to be stuck and I don't want to damage it with force. Is there a trick ?

 

UPDATE I soaked the end section with WD40 and it the pulled out spilling the cristals. All I have to do now is find where to buy some new ones.

 

This is the kit and the company has a good reputation and I did buy from them.

Read the page About us I like it when there is a person behind the product.

It seems that there has been lots of moisture going into your system. So I think it could be fair to suspect that moisture has also passed the pump into the air tubes. This can probably be seen when you open the compressor cylinder.
Once you open the cylinder do also try to clean the bottom of the compressor under the piston. In my case, we used just compressed air to blow out all the dust. But if you have had water in there then you might use some brake cleaner or WD40 or similar.
Maybe it is good to mention that the compressor can be worn so that it does not get tight even if you change the piston ring seal. The only way to know is th du the new ring and see how it goes. The design is such that the ring seal is the first to go so a new ring should fix the problem,

One thing to consider if there has been passing dirty moisture into the tubes is that the valve block has then got that dirt inside it. I have only found one post on the internet about cleaning the valve block. That was a Mercedes owner who did the job on his car. The job itself is not difficult but you need to be able to source the same size of o-ring. We here in Helsinki have a special shop that analyses your o-ring and then you get new the right size replacement rings.

Even so, I did opt to buy a new valve block. Mine did not have any fault but I thought that with 240tKm I didn't want to worry about air suspension fault. So I bought a new one from German company Miessler. They answered nine e-mails with questions I had. They specialise in air suspension on many brands and also refurbish XJ original air struts but also have their own production. These also support the CATS active damping system that our XJ has.

Here link to Valve Block if you want to consider a new

The price for a new compressor is quite ok if one wants to go that way
Here is a new Wabco compressor.

The valve block is easy to install just mark the tubes so that you get them in the right order. The Miesel valve block has connectors that work so that you just press the tube into the hole. The tube will stick when you get it into about 1 cm.

 

Beyond the dryer chamber is the vent valve solenoid, probably also just as rusty as that spring.