Hello all,

I have a 2006 Jaguar XJ8 that keeps displaying the following error:

Air Suspension Fault

However, the suspension had been repaired (before I purchase the vehicle) and works perfectly (i.e. the car does not sit low after sitting over night, rides smooth, has no issues with speed bumps/humps, does not make any noises, etc.).

Is this simply the mechanic forgetting to reset the computer? Is there someway I can reset this? Or do I have to take it to a mechanic to get this reset? Or what could I be missing?

Thanks in advance.

 

I had this problem too and it might very well be that the code was never cleared. You can go to your local Advance Auto Parts store in VIrginia and they will plug in their OBDII reader and check/clear the code for you for free, or just let you borrow it. There may be other parts stores that will loan you an OBDII reader, but my mechanic told be about Advance and that's the only one I know about for sure. It only takes 5 minutes and it's a really simple process. If you can work a cellphone you are well qualified to use an OBDII reader.

FYI, the plug is under the dashboard adjacent to the center console, facing down (on my 2004 XJ8-it should be the same on your 2006). I bought a reader for less than $100; I'll leave it in the car to travel with us.

If clearing the code doesn't solve your problem, there's a great discussion thread here on dealing with air suspension faults--it is a well known and documented issue.

Good luck,

 

Yes, clear the codes, but read them first. If yo get C2303, it could be the compressor is on the way out, unless this was replaced as part of the repairs.

 

Slightly off-topic, but this morning I saw a fellow XJ on the road with its front suspension basically on the ground due to the cold. I've seen this at least a dozen times over the past few months. Its been abnormally cold this winter here in LA, so I'm sure glad I ripped that horrible system out and put in the coilovers this past summer. Best thing I ever did to this car.

 

A normal OBDII code reader will read engine codes but will not read or erase a suspension fault code - at least the ones I have used will not. It takes a Jaguar specific code reader like the icarsoft 930 to do it.

I found out the hard way that a broken wire on the front height sensor will lower the front suspension to the bottom on both sides. I had to drive 300 miles with it that way and it was a rough ride, but I got 27 MPG on that trip with my supercharged, nose-down, low rider.

 

Hi Philwarner, Everything I have read confirms/agrees with what you said about a Jaguar specific OBD scanner. So, I purchased an iCarsoft i930. It showed no DTC codes but I cleared/erased it anyway. Now it only shows either P1000 or P1111 (I forget which). Anyway, my message center continues to show "Air Suspension Fault", "Park Brake Fault" and "Lights are Off". The same 3 messages continually rotate over and over again in the message window. I know my lights are off because I want them off. The air suspension seems perfect (sits for 3 or 4 days and doesn't drop at all and rides great) and the parking brake also seems to do exactly what it is designed to do. I've checked several relays and they all seem to be functioning properly. I pulled the battery had it tested under load. Came out well within specs. I currently have temporary tags and need to get the state inspection. Any ideas/suggestions would be greatly appreciated.

 

Regarding the Parking Brake Fault, try unplugging and replugging the Parking Brake Module in the trunk. That worked for me when I was getting that message.

 

Is it possible you used the OBDII choice on the i930? That choice will only check for engine codes and there may not be any if the check engine light is off. The first choice in the diagnosis menu should bring up lots of systems to check for DTCs, and the suspension system should show one or more if the message center gives you the suspension fault; it will probably be the C2303 – Reservoir Plausibility Error.

The "lights are off" will be triggered if the dash sensor thinks it is too dark; mine does this too. Not sure about the parking brake warning, but it should have a DTC in the parking brake section of the diagnosis.

BTW, you can press the reset button on the lower left dash panel below the A/B button to make the messages go away from the message center but the amber warning light will stay on to remind you that they are still active and they will return when you turn off and restart the engine.

Try the i930 again and let it automatically chose the systems that may have DTCs; I think you will be surprised how many there might be.

 

First of all thanks Philwarner. You were right about the icarsoft. It has a lot more options than my old Innova scanner. I guess I should have read the manual before using it (how many times have I said that). Anyway, I did as you suggested and I got 2 codes. A C1885 and a C1830. I tried clearing them to no avail. Also, pressing the "reset" button didn't clear the fault messages. But..I now have codes to track down. Perhaps there is actually something wrong after all. When I look up the C1830, it talks about Air suspension compressor relay circuit malfunction and the C1885 states right-hand rear height sensor signal circuit malfunction. Well, at least now I have a starting point. I kind of miss the old days working on my 55 Chevy, no computers just a lot of tuning. :-)

 

I'm at a loss. Regarding my C1830 code (Air suspension compressor relay circuit malfunction), I've read posts regarding relay #4 and relay #1. Both seem to test as okay. When I apply 12 volts to the 2 appropriate pins, I hear a "click" and I get zero resistance through the other 2 pins. When I remove the 12 volts, I get infinite resistance. These relays were located under the hood on the passenger side of the car. Am I testing the wrong relays? The chart that I was looking at says R1 in the front power distribution controls "Air Suspension" and that and R4 is "Wiper On/Off". Not sure what to check next. Unfortunately, the clock is ticking on my temp tags and I assume it will fail with these messages displaying. I really don't want to have to bribe the Maryland Inspection to pass me. :-)

 

Hi denajohn,


The first things I would check would include the ground point used by the Air Suspension Relay (R1), which provides power to the Air Suspension Compressor. The ground point is behind the right headlamp and I believe it is the lower of the two ground studs located there. Here's a link to photos showing how to clean the ground points, and note that the torque spec for the nuts is just 6.5 ft. lbs., which is barely more than hand tight. Several members have snapped the ground studs off of the body by overtightening the nuts:

https://www.jaguarforums.com/forum/x...2/#post1156791


Regarding the rear right height sensor, I would first check its electrical connector for looseness or contamination and clean the terminals with zero-residue electrical contact cleaner. Also check for any damage to the wiring harness. If you don't see any problems and cleaning the connector doesn't help, the sensor may have a problem or there may be an issue upstream in the wiring. All three wires of the sensor connect to the Air Suspension Control Module (ASM) which is mounted behind the rear seat and its ground point is also there. Cleaning the electrical connectors at the ASM and its ground point might help.

Cheers,

Don

 

I pulled the rear seat bottom and back today. Did not see the ASM. Where is it? Did not pull all the cover off behind the seat back.
Want clean the contacts and ground. The 2302 error message keeps returning.
The compressor has a new seal and the grounds in the truck and the three behind the headlights have been cleaned.
Car is correct height, maybe a little lower than normal all the way around. It does not drop sitting for a week.

 

Hi Panelhead,

The ASM is on the right or passenger side behind the rear seat back. It is riveted to the rear bulkhead and has about four electrical connectors attached. The two I've seen are marked WABCO.

The C2302 diagnostic fault code seems to be most often caused by a worn ring in the air compressor such that the compressor cannot pressurize the system within the allotted amount of time. C2302 can also be cause by an air leak or disconnected air pipe, but your suspension is not behaving as though it has a leak. Has the suspension continued to misbehave even after the compressor piston seal was replaced? If so, are you confident that the seal was installed in the correct orientation? If it is installed upside down it will not seal properly at the lap joint and will not be able to pressurize the suspension in the alloted time.

You can download the full DTC Summaries manual here:

https://www.google.com/url?sa=t&rct=...03388427,d.cWw

Cheers,

Don

 

I did not remove the entire rubber mat behind the rear seat back. Never saw the unit.
The seal on the compressor is installed correctly, I made sure the locator pin was in the notch.
The problem has gotten worse. The suspension failure light and code comes on in less than five miles now. Sometimes one mile.
The only issue is the hard ride once it throws the code.
After the seal and cleaning the grounds behind the headlights seemed to help a little, I thought it was fixed.
The ASM module is my next attempt. Then maybe electrical tape on the instrument panel. I am from Nashville.

 

The seal can have the locator pin in the notch but the seal be upside down so the wider finger of the lap joint opens up during the compression stroke instead of being forced more tightly against the narrow finger. Here's the correct orientation:




Regarding the ASM, you don't need to remove the entire rubber mat. When you remove the seat back, lift away the mat in the area where a rear right passenger's back would make contact about halfway up the bulkhead. You'll see the ASM, which is a black metal rectangle marked WABCO with four or more electrical connectors along the lower edge. I have photos in a file somewhere and will try to find them.

Cheers,

Don

 

If the seal was upside down the "gap" would be at the bottom of the seal not the top. I am sure I had the gap at the top of the piston.
I can pull the back seat in 20 minutes. Back in is 10. The compressor was all day the first time, might be four hours if done again. Getting the springs and such right kicked my butt.
The compressor seems fine, the original seal only had a little wear on one side.
I will try again tonight.
Might make it to Nashville soon. Usually stay with family in Hendersonville. Will hunt you up.

 

I'm sorry to push the possibility of the seal being in wrong, it's just that some of our members have done that and your symptoms seem so much like a compressor that isn't pressurizing the system in the allotted time.

One other possibility comes to mind - is it possible your compressor's exhaust valve is stuck partially open or the outlet air hose fitting is either not quite tight enough or too tight (damaged threads)? You could probably test for this easily by running the compressor until it shuts off, shut off the engine and then listen for escaping air from the compressor area. Sorry to keep bringing up bad possibilities.


Please do! We'll grab coffee or lunch if you have time.

Cheers,

Don

 

A big +1 on both over tightening the air line into the compressor and not properly installing the piston ring. Or possibly the air line might not be tight enough. Spec calls for the brass fitting/olive to be discarded for new. More times than none you can reuse. I marked my brass fitting to the housing to ensure proper clamping force without over I tightening it.

I'm extremely mechanically competent (I changed all tensioners and chains/rails on my 4.0 motor twice) and I screwed up the piston ring install.

I had similar symptoms after the piston ring install. When I flipped the piston ring back properly, no more air suspension issues. Also, I found my female plastic threads were partially stripped.

I purchased a shot compressor on the cheap and swapped that part over and zero issues since...

Good luck

 

If servicing the ASM does not help I will pull the compressor again.
I cleared the c2302 code last night and left the car idling. It came on in a few minutes. Turned off and restarted. Let it idle for 15 minutes and it did not come back.
I will check again tonight. But did not hear the compressor running. Need to get out and listen by left wheel well.
I may have under or over tightened the air hose. Laying on my back with car on ramps all day was very fatigueing, Most likely over tightened. And did not replace olive.

 

+1 on cleaning (unplug and replug) the ASM connectors, when you find it!