After bathing the entire suspension system of the GL in soapy water last Saturday, I have gone ahead and ordered a new valve block, compressor and Autel MD808 code reader. Will be interesting to see what codes come up. I have a hunch that if it shows a ride height sensor out of spec, I will still be scratching my head as to whether the air shock is leaking, or if the valve block is leaking, but more information to digest is always handy. I have read many, many threads on at least three different forums about the Airmatic suspension (this is why I asked for the specific link), and 9 times out of 10, it boils down to leaking air shocks, but I just can't find any evidence that the shocks are leaking, either from their rubber bodies, or from their connections.

I recently got half way through changing out the rear brake pads on my VW Tiguan, when I was confronted by the requirement of an advanced scanner/shop system as it was required to back-off and reset the electronic parking brake (luckily I have the VW specific system on an old laptop). It is definitely getting to the point where even the simpler wrenching can't be done without accessing the central nervous system of these vehicles.

Will update when my goodies arrive.

Wise guy... ;)

Jon, have you tried removing/inspecting/cleaning/greasing the level sensor arms? I'm not convinced this is your issue, but it's easy and free to do.

I wonder... with the relay removed AND the level sensors disconnected... try driving around. I imagine you'll get an error code. But (and this is just my non-21st century brain thinking outloud here) if there's nothing telling the "computer" to adjust the bags (in this case only letting air out because the compressor is disabled), then that should eliminate the level sensors as possibly culprits? If, in fact, the car still drops. If it doesn't drop... it might mean the level sensors ARE the culprit.

If that Autel is like the MBII I have, you can see the readings (I think "live?) from each sensor.

Do the soapy water trick with the truck at normal ride height, full pressure. You tested it with completely changed height and pressure.

Get yourself a cheap wash bottle and fill it with soapy water. Crawl underneath for the rear and turn the steering wheel one side to the other for the front. Look for stoner spit on the bags.

OK--Finally! I bought a new compressor and valve block, just to have parts in hand--have a 60 day return window, so if I don't need them, I'm not stuck. Also bought a more capable scanner. I had heard that the Autel MB808 "professional" would do what I needed, so bought one. Found out, to my distress, that there are two identical models, with the same packaging, etc., one is the MD808 base model with only 4 functions, and the other is the MD808Pro, which can monitor all systems. Had to return the MD808 I bought by mistake, and purchase an MD808Pro, which was only $20 more (and I think they are actually the exact same hardware, just sold at two different price points/capabilities, all software controlled). Anyway, I got the thing working last night, and scanned the GL today. Codes I got on the Airmatic were as follows:

5505 Recovery times during filling of air suspension strut is too long
5508 The pressure line system leaks
5503 Recovery time during filling of central reservoir is too long

Hmmm... Sounds like there is a leak, and that it takes too long to refill...Interesting that it doesn't show any of the wheel specific ride height sensors out of spec...

So my conclusion/path forward is that either I have a leaky line or a leaking valve block-- so swap out the valve block.

Compressor may have gotten worn out trying to keep up with the leak, but I'll do the valve block first, do some road testing, and then change out the compressor if the "slow fill" errors persist. Unfortunately, this is the path forward I had in mind without the scanner, but it feels like my intuition has at least in part been confirmed (unless someone out there who knows better what these codes may imply can fill me in).

Points to compressor so do the compressor first - much easier and also reversible. Unless your valve block has visible leaks using leak detector spray, leave it alone. Replacing that thing is rarely necessary and fraught with introducing new leaks.

Jonathan,
Can you tell me how youresolved your AirMAtic issue? Did the valve block fix your problem? Thank you! I'm also tracking down a weird dropping of one side then another on my GL450.

My apologies for not following up. Well, I usually spend way too much time dithering around experiencing "analysis paralysis," but then when I have parts in hand and a few minutes to do some work, I throw caution to the wind, and every part I have at the problem. That is what happened here. So...The valve block is hidden behind the compressor, and I decided that since I had to remove them both, I would just replace them both and see what happens. The good news is that so far, all air shocks are maintaining their fill, and the "airmatic malfunction" warning has not re-manifested, so I will knock on wood and say that I have solved the problem.

Here are a few caveats: In the new normal of Covid Life, the GL spends most of its time in the garage, and another car is used for the local trips to buy toilet paper and beer. So I am not getting a lot of miles on it, BUT, even after not being driven for a couple of weeks, there is no obvious loss of air in any of the shocks. I have hunted leaking airbags several times now, and am reasonably confident that the bags are (still) not leaking. I don't have any hard evidence that the original valve block was leaking. All my research suggested that the valve block was not a failure prone item, but I figure I am in Houston, where the air is 60% water vapor, and at least 20% Benzene, so maybe the statistics for valve block failures worldwide are pretty small, but if there are rubber seals involved, I bet Houston failures are high.

I still have the old valve block, compressor, and a failed "linear" compressor from an LG fridge. If I find the time, I might try and section them with a band saw and try to see if there are any smoking guns to be seen.

Hope this is of some help!

I have the exact same problem with my 2012 GL450 any conclusions or follow-up would be welcome.

Thanks for your persistence, jonathonkreb!

Hi,

Another month or so has gone by, and the shocks are still holding air just fine. Nothing observable as an Aromatic issue, no "Airmatic Malfunction" graphics, etc.. So I will knock on wood again that I have gotten the problem licked. Still haven't sectioned the valve block, either, as my attention is now focused toward a front suspension rattle, that is probably the result of rack and piñon bushings (and the typical power steering fluid leak from the top of the rack).

I hate to suggest that the valve block was a contributor to the issues I was having without any evidence, but that is where I am. I might have solved the problem equally well by just replacing the compressor. Just don't know how long they are supposed to last. Even though I only have 83k miles on my 2008 GL, age really wreaks havoc on seals, bushings and other rubber stuff, especially down here (note the benzene comment above).

83k in that environment, assuming your drive like to he average houstonian, is within the failure interval for all airmatic components.

they do not last the life of the car in most cases.
one should expect to replace all four bags, maybe a compressor and perhaps a valve block at around 100k.

I have a hunch your compressor is tired and those codes aren’t leaks, they’re because the compressor isn’t putting out threshold pressure (16 bar w/in 30 secs). It’s just not putting air into the system at a rate it needs.

can your scan tool do the MB DAS built in leak tests? DAS can test output pressure, leaks from compressor to valve block and leaks from valve block to central reservoir.

Well, then, I should be good to go for a while, as everything but the air lines and the reservoir have been replaced within the last 20k miles. I went out and scrounged around my garage looking for the old valve block, as I thought it might be informative to just cut it up and be able to say one way or another that it contributed to the leak, but, of course, it has gotten lost in the mountain of half-finished projects. Found the compressor though, just no valve block. Oh well... Some day when i am NOT looking for it... there it will be. I might not own the GL by then, but you never know!

Contributing to this Mysterious Airmatic Malfunction Thread: When I was in the throes of struggling with a dying battery, I got an Airmatic Malfunction error message on the dash. I chalked it up to low battery weirdness.

I did notice slow clicking from under the hood, where the valve block is.

However, after changing the battery, the error message returned. Possibly just the old DTC triggering a new dash message? I pulled out the computer and read 5503 Recover time filling central reservoir.

Mite just change the valve block for the fun of it. Not an expensive part.

So I received the valve block today. It looks like this:

Now, that does not look like what's under the hood - or maybe I'm looking in the wrong place. There is a steel box under the hood, with six air lines going to it, but it looks nothing like this. Can y'all help enlighten?

Edit: Nevermind, I'm officially retarted. I was looking at the ABS module.

+1

I've been on these forums long enough to KNOW not to second guess you on this one.. when you're right, you're right. :rolf:

My valve block is behind the compressor, and only really visible if you remove the feltish fender liner of the front passenger side.

good luck!