I used the car last Saturday for a trip of about 190 miles and it has stood until today when we went to a restaurant. On starting the car, almost immediately I got a fault display "air suspension fault". Since last Saturday we have had very mild weather, but damp, and a lot of rain, but no frost at all at night.

Despite the fault display the car drove completely normally and I could detect no difference in the suspension at all, and around here the roads are pretty bumpy, especially the back lanes we mostly used. On arrival at the restaurant, I switched the engine off, and then on again, but the fault was still there. However, when we left to go back home about an hour later, the fault had disappeared, and again the car felt completely normal.

Now I know these cars like to tell you all about faults however minor, (this must have infurated the first owners), and there are various things that can go wrong, like the compressor, but at 38k miles and with full service history should I be getting these things ? Car was last serviced at the local main agents about 3 weeks ago, (70k service as car is 7 years old).

 

Your problem is much like mine in that on cold days, not necessarly frost, the front settles way down and throws the "air suspension fault" warning. Sometimes it goes away on it's own and sometimes the car hyper inflates all shocks and stays that way for 8 or 12 hours before fixing itself. I can't explain the sequence logic because I don't understand the system well enough. But I do suspect 1 or 2 leaking front air shocks because the settleing occurs only in the front.

Accordingly, I have constructed 2 of Brutal's test fixtures and am awaiting a cold day here in central Florida to to try an isolate the offending shock. Catch it in the act so to speak. I will probably have to wait till Dec or Jan for said cold day. My bet is that you have a leaking shock that the system has detected and that your comperssor is ok for now. I would also bet you are in for an interesting Winter if the situation is left unattended.

KBO mate. Do keep us posted.

 

I did notice that the front rises slightly on starting after the car has been standing for a week. However this did not generate any fault previously. I will check the air connections.

I will certainly not leave the problem unattended, but as a busy man, it may have to wait some days before the agent gets to look at it.

 

I also notice a small upside move of the front of th ecar after one week rest

about 1,5 cm

measureed the distance between upper point of the wheelarche and floor

is 70 to 71 cm after a run , and 69 to 70 after 3 days left

Does anyone knows the average lost of height ?( must depend of temp )

All the post about suspension are very useful , even if a little bit frightening !!

Thanks for the lot of informations got here

Phil

XJ8 4,2 2006 executive ,

 

I have the same issue, but mine seems to happen when it's more humid or raining and also when it gets cold (cold being 50-55 degrees F around here). The local dealership said it might be the left front shock or it might be the compressor, they don't know. But it drives fine so I'm gonna keep driving it until one of the shocks actually fails, or the whole front end nose-dives. Then we'll see.

 

The X350 training guide I have has some hand written notes by the leakage section and says:

Leakage
1mm per day
10mm per week
1 deg C = 1.2mm change



TSB JTB00067 about air spring diagnostics says a spring should be changed if there is an 8mm or greater drop over 24 hours.

The process involves putting the suspension in to transportation mode, measuring the height then measuring it again after 24 hours. This assumes that the car isn't touched during that period.

There is also a formula to apply if there is an ambient temperature difference of greater than 2 degrees at the time of the two readings.

Example. X = ((25ºC - 20ºC)x 1.5mm) + 8mm => X = 15.5mm

 

Mine drops every time I shut the car off. When shut down, after about 30 seconds, I hear air pressure leave the system and the car lowers. When I turn on the ignition(do not have to start it), it rises again. It has done this for 5 years without any problems or warnings.

 

An update.........

Used car today for visit to local supermarket. This will be 2 days after the fault came up.

Result - no fault this time ! Also the car did not laizily raise itself like a camel this time.

So it seems I may have a small leak that manifests itself after 5 days of standing.

 

The front of my car has always risen a little when I start it each morning. Last winter I started getting the "air suspension fault" error. Seems to happen only when it's really cold; below 30 F. Dealer doesn't think it's as issue. Hopefully yours isn't an issue either. It's terribly expensive to repair.

 

Autumn here in the UK has been exceptionally mild so far, (unlike last year !), so it is not the low temperature causing it, Ithink. If there is a small leak, standing the car for several days, as I do, is likely to show it up as the air pressure drops.

I am going to have a look around the car, as I read somewhere that somebody found the air line connection to the spring unit had a slight leak and just needed tightening up

 

How expensive is it to repair would u guess?

 

Many members on this form have reported that replacement shocks (dealer installed) are $1,500 each. If you search the threads you will see some related posts. If the compressor is shot then you are looking at about $3,000 (again, dealer installed).

On a side note I started my car this morning and got the "air suspension fault" error; looks like my problem is progressing... it was only 42 F. I'll report back after I have the dealer look at it, again.

 

Another update.........
Got another suspension fault this evening, after about 10 minutes. I was waiting in a queue of traffic when it suddenly lit up. Yet car seem perfectly normal, suspension works OK, nothing unusual.

I was wondering whether the connections to the suspension height detectors can get corroded and send false messages, as they look very exposed under the wheel arch.

Can one obtain the fault codes without using a reader ? On my old Rover 75 it was possible via pressing a combination of buttons on the dash to list the fault codes in occurrence order

 

I'm guessing but it may be the compressor. Read the codes: 23?? is a compressor plausability fault.Is it cold there at the moment?

 

Another fault light last night, but none this morning on the way to work. So I have booked it in to the main agent near me for a diagnostic. Service chap said compressor failure is the commonest fault, but I knew that anyway.

 

Fraser,

Any word from your service provider on suspension issue?

The world wonders.

 

I decided to do some investigation to see if any of my air lines are loose (my fault messages are becoming more regular in sub 40 degree temperatures). I lifted up my spare tire and found about 1.5 to 2 inches of water in my trunk. That much water submerges part of the air tubes (or electrical wires - I don't know what's what), and the lower portion of the air storage tank. I had to pull out the two drain plugs to get the water out. A little more water and my fuse box may have been compromised.

So now I have two problems. Hopefully the water was the cause of the fault messages; it certainly makes sense. I'll report back after I drive it the next few days.

Anyone with suggestions on finding trunk leaks please come forward!

 

Have a look at the attached.

 

Thanks a lot for the TSB! That's some great info. Perhaps we can get the Moderator to make this a Sticky. I'm sure others are having similar issues.

I'll report back on the air suspension fault after I've fixed the leak.

 

thanks, snagged the TSB link and placed it in the FAQ thread...which BTW really needs a single organizer to adopt it as his own. Either one of you guys want to accept such a role?