X164 (GL420 CDI) airmatic suspension malfunction ?

[CHF]

I was wondering if anyone can shed some light on an intermittent suspension issue that triggers an malfunction car icon on the dashboard (see attached) ? While triggered suspension settings are locked in sport mode and cannot be changed to normal or comfort. Also when switching gear to parking position there is no warning signal.
Any help would be appreciated before a costly trip to the dealer for investigation.

Many thanks
Chris

 

[cagliere]

I have a 320GL and got the same thing when I was messing around with the height adjustment in traffic. The car bounced all the way home in the highest mode.
I switched the engine on and off a few times and it reset itself.

Took the car to a merc specialist with a Star machine. Could not detect the problem but confirmed that there was an issue! Bye bye £80 for diagnostic. Turns out Star machines can't diagnose everything.

So having spent four months looking at websites trying to find a solution I have concluded that a merc dealer is the only place to go.
For info the suspension has the following components that can fail. Non exhaustive list of course.

Air pump
Air relay
Strut with airbags/bladder
Valve block controlling air pressure to the struts
Computer of course
Ride height sensors -one at least in the rear of the car on the axle
I also believe that there is a steering angle sensor somewhere
Each strut has a height sensor ( just look underneath the arches and you will see a meccano looking set of arms size of a fist.

Diagnosis is the real issue of course

If your suspensions will not raise it is a burnt out pump caused by a knackered relay which has stuck causing the pump to burn out from continual running
Valve blocks can errr block causing uneven raising and lowering or preventing one side reaching its full indicated position

Of course if the height sensors fail then ride height will be different

Some of the parts are cheaper than others
I know that the pump is about £450 wabco or genuine merc is £650 approx (made by Wabco with a nice merc stamp on it)
The pumps in the older models leaked at a T joint which is made from a piece of plastic. Merc modified this and eliminated the T piece so no more leaks. Replacement parts might still have the old T watch out.
If the strut is leaking it is due to the rubber bladder splitting. Arnot industries make an as good replacement if not better than the original 50% cheaper than a genuine part.

At speed my left rear feels like it is going to lose a wheel when I go over a bump. Curiously the left rear sometimes sits higher than the other three sides. The whole car I think is meant to lower 10mm above certain speeds.

Anyway not a solution to your problem just some comfort in terms of what might be wrong.

Of course as all mechanics say...
It's not the parts it's the cost of the labour.

Be interested to know if you get a solution.

I have a warranty I purchased separately when I bought the car so will be giving that a run at a dealers at some point.

 

[CHF]

Thanks for sharing this info, it is reassuring and worrying at the same time .... So if stop by a merc dealer and get a diagnosis before I do, I would be interested to know what error code they picked up and the investigation they carried out. Do you know if they charge a flat fee for this sort of investigation ?

Mine is now stuck in sport mode, so lowest setting and will not raise so I would tend to believe something wrong with the pump ?

 

[CHF]

Anyone ?

 

[Bobby Dazzler]

I would look at the ride height sensors before anything else. They're known to fail and compared to the rest of the Airmatic system, relatively cheap to replace.

 

[MB8701]

I don't know if it will be the same but the L322 range rover I used to have was well known for the ride height sensors going faulty but also being dirty as they were tucked up aware under the wheel arch.

If they get covered in dirt and don't get cleaned they sometimes go a bit crazy and think the ground is closer or further away than it actually is causing the ride heigh to be strange on certain corners.

The fact it says malfunction and nothing shows on STAR suggests to me something is tempremental which once again suggests a sensor more than anything.

A few tricks to try and accertain what it might be is.

Park on a perfectly level ground and check the height of each coner

Check and monitor each corner to see if it bobs up and down - even if its
slowly - this indicated a puncture in the airbad - I had this once on an ML420

Push the airmatic button to raise and lower. It should go in the highest setting within I would say 30 seconds - If it takes a minute then the pump is on its way out or knackered. My range rover used to throw an error everytime it took it too long to raise and lower the car

I have heard or other tricks where people raise the car to the highest setting and you can clearly see the airbags in each corner - people put soapy water on them to see if bubble arise to show a leak.


I would try the first few I suggested......
Sorry I cant be more help.

 

[gl boy]

Had this issue on my gl320 8 months out of warranty !!!! They changed £7000 worth of parts , and thankfully again this was done under a good will gesture from Mercedes , but hearing people have had issues I'm wondering if it's a problem with the air matic system :-/

 

[cagliere]

GL air suspension

Sorry been away for a while and just noticed that this is still going...

I had my car put on a star mahcine with a Merc specialists could not diagnose a problem. I had it serviced by an official Merc dealer. Same issue computer says no but eyes not used by Mechanic!
Then car broke down in Spain ( got it back after four weeks recently- proposhaft broke!) Spanish Merc dealer also put it on the star machine and reset the software!! They too could not see the problem for what it was. I am now convinced that the ride height sensor is knackered as the Spanish dealship also said that they needed to clean the sensor but think it may have perished; strangely lacked courage of conviction to replace it.

There is a rear axle sensor £119 from Mercs but today the dealers could not find the actual ride height sensor on their computer so I will have to point it personally with my digits....

 

[BlackC55]

If its coming up with a warning there must be fault codes.

 

[cagliere]

If its coming up with a warning there must be fault codes.

Aha! No fault codes!

At last I found out what was the cause of the suspension issues?

This week a relative replaced the rear ride height sensors. First the left rear sensor because this side was always higher than the rest.
We did not notice that when the sensor was removed the car did not drop!

When we replaced the right rear sensor as soon as the sensor was removed from the car that side began to lower!

So that threw me and I gave up.

Booked it in to Mercedes GATWICK for a diagnostic. And did not take it to my local Benz dealer as they do not seem to be able to use a Star machine.

The GATWICK guys were spot on. Took me to see the car on the ramp which they do not normally do to show me what they had found.....

The front ride height arms are made of plastic and had become soft which caused them to flex and bend. What this meant was that they were not moving the control arm on the sensor.

As a result the EcU decided to lock the left rear at a certain average height and then in effect the shocks stopped working. It explained everything in terms of the ride height.
And bouncing down the road.

What an absolute relief. The cost of the parts to supply and fit is £60 odd.
They reset the levels and I am having the car geometry done on Monday. Drove the car back and the difference was obvious and instant.

Thank you Mercedes Benz GATWICK. You have restored my faith and my long and expensive quest is nearly at an end!