We have written about Range Rover air suspension before and the physics are the same, but the Mercedes system has its own character and its own failure order. If you drive an S-Class, E-Class, CLS, ML, GL or GLE on air, this is the sequence worth knowing.
What AIRMATIC actually is
Instead of steel springs, the car sits on air springs — rubber bags inflated to a pressure the control module manages. A compressor supplies the air, valve blocks route it, and ride height sensors at each corner tell the module where the body is.
It rides beautifully and it self-levels under load, which is why Mercedes fitted it to everything heavy and expensive. The trade-off is that it has moving parts and rubber where a conventional car has a coil of steel.
The first fault: a leaking air spring
The bags are rubber. Rubber ages, and it ages faster in a climate that cycles it between a hot car park and an air-conditioned garage every day for years. Eventually one develops a leak — usually a fine one, at a fold or a crimp.
You notice it as the car sitting low on one corner in the morning, then rising to normal a minute or two after you start it. That is the compressor doing its job. The system is working exactly as designed and quietly telling you something has failed.
At this point the repair is one air spring.
The second fault: the compressor you did not need to buy
Here is the cascade, and it is the reason this article exists.
A leaking spring means the compressor runs to top it up. Not once — repeatedly, through the day, and every time the car is started. The compressor was specified for occasional levelling duty, not for continuous replacement of air that is escaping.
So it runs hot. It runs hot in a city that is already hot. And in time it either burns out or wears to the point where it cannot build pressure, at which point the car drops onto its bump stops and stops being driveable.
Now you are buying an air spring and a compressor, and possibly a drier, because the same over-running usually saturates that too.
The whole of the advice here is: fix the bag when the car first sits low. Not when it becomes inconvenient. Not when the warning appears. When you notice it kneeling in the morning.
What else fails, and what it looks like
Valve block: the car sinks at one corner or holds pressure unevenly, and the leak is inside the system rather than at a bag.
Ride height sensors and their linkages: the car sits at an odd height, or the suspension warning appears with no leak anywhere. The linkages are exposed and they corrode and seize.
Relay and wiring: the compressor relay is a known weak point, and a compressor that never switches off will eventually kill it.
Struts on ADS-equipped cars: the damper and the air spring are one assembly on many models, which changes what a repair involves and is worth establishing before anyone quotes.
The bad advice worth naming
You will be offered a coil spring conversion kit — steel springs replacing the whole system. It is cheaper up front and it is genuinely permanent.
What it also does: removes the self-levelling, changes the ride the car was engineered around, usually leaves a fault stored in the module unless it is properly coded out, and reduces the car’s value to any buyer who wanted an AIRMATIC car. On a car worth keeping, it is a decision to make deliberately rather than because it was the cheapest quote in the room.
We will fit one if you want one, and we will tell you honestly what you are giving up.
What we do
Diagnosis first: read the suspension module rather than guessing from ride height, check each corner’s live sensor values, and pressure-test to find where the air is actually going. A car with one sagging corner does not automatically need that corner’s bag.
Then a written quote separating parts from labour before anything comes apart. More on the system on our suspension and steering page, and on the marque on our Mercedes service page.