About 3 weeks ago the info center said "Air Suspension Fault", but when I restarted the car there was no fault message. Yesterday, the same thing occurred, and again no fault on the next restart.

Had a chance today to hook up IDS/SDD and look for any air suspension related DTCs. The only one I got was:

C2302 -- Leveling plausibility error.

I installed BagpipingAndy's kit about 9 months ago, and there is no lowering of the car or any indications of leak.

Any ideas?

 

Check your battery condition and voltage.

 

Agree with abonano, always check the battery is good. Even if the battery is slightly under, it can cause all kinds of things to not work properly. With that said, the XJ 350 model with that code were prone for the air suspension compressors to fail.

 

Clear the codes off, check the battery, then if the fault message comes on again, read the stored code(s), then report here again.

 

I just had that code along with a C1889 (left front height sensor open or short to ground) due to a broken wire inside the sheath of the front level sensor connector. Easy to check with the left front wheel removed.

I'd guess a C2302 might also be an intermittant at a rear sensor.

 

Just a quick update.

Took a look at the compressor relay (R1), and noticed that it wasn't the brown OEM type, but instead a generic relay. Struck me as odd, then I remembered that I had to replace the entire front fuse box because one of the board soldered relays had failed on mine. (Here's the world's longest thread about how I eventually found the problem: https://www.jaguarforums.com/forum/x...-132586/page6/).

Since I kept my old fuse box with all the relays and fuses as spares, I swapped out the relay for a OEM one. Cleared all the codes, and will report back if the relay was indeed the issue. So far so good.

 

this error: C2302 -- Leveling plausibility error,


suggests at one point it couldn't understand or adjust the level, check level sensor wiring and battery, any other strange electrical issues?


how was the cylinder when you fitted the kit, any deep scoring?


best regards


Andy

 

Bench test the relay you removed to rule it out as faulty...

 

Hi Andy,

The cylinder was in very good condition. I didn't wait for the compressor to fail or to start to have issues, I instead put your kit in as a preventive maintenance measure at the time.

No other strange issues or codes, and battery is a nearly new Bosch AGM.

 

After going nearly a week without a fault, this morning I got "Air Suspension Fault".

It was the first use of the car after sitting in the garage overnight, and it occurred in less than a mile into a short trip (1.2 miles total). Restarted the car at destination, fault gone and no fault on the return trip. Had to make the identical trip to pick up my daughter 3 hours later, and no fault during the round trip.

Pulled these ASM related codes:

C1830 Air suspension relay drive circuit fault

C2302 Leveling plausibility error

After pulling the codes, I disconnected the battery and measured the height of each of the wheel arch. Will wait to see if there is lowering at any corner over the next few hours.

Odd that after swapping out the relay, I got the C1830 DTC.

 

Well overnight the front height went down about 1/4" (6-7mm).

Not sure if that is enough to indicate a shock leak, or normal overnight settling due to weight of the engine.

Given that the fault is only occurring after the car had sat overnight, I expected a more significant drop over nearly 24 hours.

 

I am also dealing with code C2302. I have installed Andy's kit in my pump, and the car does lift and the pump shuts off. In looking at it after it shuts off, I think it still looks low in the front. Driving a few minutes will cause the AIR SUSPENSION FAULT message to come back on, and the only code that resets is C2302. 2008 XJ, 78k miles and I don't think it has any leaks. I am not sure what to do next. Any guidance would be appreciated.

 

Hi, did you perform a clear of the stored suspension code? This has to be done via IDS/SDD or WDS dealer level diagnostic system. The code will not disappear unless cleared from the suspension module.

 

Yes I have cleared the codes, 4 or 5 times now. Each time C2302 came back, after the AIR SUSPENSION FAULT message came back. That message will be off for the first few minutes of driving after restarting the car, whether or not the code has been cleared. The only other code that resets after clearing is U3FF6, which I have not investigated yet. I drove the car half an hour after clearing all the codes yesterday, scanned it this morning, and the C2302 and U3FF6 were the only two that had set again.

 

Quick Update

I've been able to reproduce the conditions that consistently trigger the fault.

If the car has been unused for at least 12 hours, and I then drive the route to my daughter's school, it will trigger the fault. I believe the route is key, because the streets and traffic won't allow going 25mph or above. IIRC, the compressor won't run unless you are going above 25mph.

So my guess is that one of the shocks has a very slow leak, and that given enough time it leaks to a point where there isn't enough pressure in the reservoir to bring everything to the right height. If I take another route where I can quickly hit 40-45mph, the compressor can run and make up the difference with no fault is triggered.

A couple of years ago I made a set of the test valves from Brutal's great instructions here:

https://www.jaguarforums.com/forum/x...agnosis-42703/

So as soon as I can spare the time, I'll use them to set up a test and see if I can determine which corner might be leaking.

 

Thanks for that observation. I sometimes drive a mile or so before I get above 25 MPH which may explain why the ASF message comes on early at times and sometimes not at all such as at night when I know the neighborhood children will be inside and I can drive a little faster.

 

Update

I had a chance yesterday to dig out my "Brutal" test valve and put it to work.

I was a little surprised that neither of the front shocks lost pressure during all day testing as I had convinced myself it must be one of the fronts leaking. When I was going to quit for the day, a neighbor walking by and casually mentioned what a beautiful day it had been. This made me realize that it was a good 15-20F degrees warmer than it had been the previous week.

I pulled the car into the garage and set up the test valve and pressured it up to leave overnight. Eventually the temp dropped enough to expose the leak in one of the front shocks.

I decided that I'll be a guinea pig for the forum and have ordered one of the Suncore remanufactured units to see how how it performs. Once it arrives and I have it installed, I'll do a final update.

 

Thanks for the update. It was mid 40s here yesterday and going for a drive I made sure I got up to 30 close to the house and drove around all day without an ASF message. It dropped below freezing last night and this morning my wife said she drove to chruch without an ASF but did have one on the way home. Checking the codes it was the C2303 reservoir plausibility error again, but the ride height is normal as usual.

 

It sounds like you have the first warning signs of a leaking shock or a worn compressor piston ring. I highly recommend making yourself one of Brutal's testers:

https://www.jaguarforums.com/forum/x...agnosis-42703/

Particularly before warm weather sets in and hides the culprit.

If you haven't installed BagpipingAndy's compressor rebuild kit, it's incredibly cheap and fairly straightforward to install. Good preventative measure, but could also be the cause of your issue.

 

Yes, I agree. Andy's kit is in the glove box and that's my next step after I get my new Pirelli P7s on the front and a 4 wheel alignment done. So far it doesn't seem to leak down except when a wire broke on the front height sensor and let the front down to the stops.