The most common reason why the Mercedes-Benz malfunction light comes on along with the car symbol and ⇫ UP arrow is due to the failure of the air suspension compressor. The air suspension may be too weak to raise the car, the air release valve may get stuck, or the air suspension compressor may stop working completely:
List of reasons why Mercedes-Benz malfunction light, car symbol and up arrow come on:
- Air suspension compressor - The compressor may work but doesn't fill the reservoir fast enough.
- Valve block
- Leaking airline (white tube)
- Air release valve (mounted on the air compressor, may not release air)
- ADS valve faulty ( mounted at the body of each air strut).
- Wire harness. ( usually wires or connectors to the ADS valves)
- Accelerator body sensor - yes, this can fail too and cause the malfunctioning warning light. It's a good idea to read all the codes.
- Level sensor failure
These problems can trigger the air suspension malfunction message and car with the up arrow.
To find out which one is the problem, you will need to read the fault codes from the air suspension module. You can learn how to read Mercedes-Benz fault codes yourself using our guide on Reading Mercedes-Benz Fault Codes.
AirMatic is a robust system that requires almost no maintenance and rarely fails. Even when that does happen, the likely cause will be in one of several components we listed above.
In this article, we will find out why they do fail. This should help you quickly narrow down the problem and avoid costly mistakes while fixing the AirMatic on your car.
Common Causes of Suspension Malfunction
The heart of every AirMatic system is its compressor, whose job is to provide a steady flow of pressurized air. This is a simple device, similar to those used to inflate a flat tire, with only a few moving parts. It has a cylinder with a pair of valves and a piston inside it that goes up and down. The whole assembly is powered by an electric motor, which is one possible failure point.
When the air suspension compressor fails, you may get a fault code such as:
- Recovery time during the filing of the central reservoir is too long.
This code can be caused by a faulty air suspension compressor failure and a damaged airline or faulty valve block.
The piston rings will wear out in most cases, preventing the compressor from generating enough pressure.
The air compressor may run and seem to work, but it takes too long to generate the required pressure, which means the compressor is too worn out and needs to be replaced.
Specialized repair kits help solve most of these issues if you want to save money and rebuild your worn-out air suspension compressor. Air suspension compressors are very inexpensive and easy to replace. Usually, it is not worth trying to rebuild an old unit.
ADS stands for adaptive damping system. These valves change the suspension setting between SPORT and COMFORT or NORMAL. The ADS valves are mounted at the body of each air strut.
ADS valves can fail and trigger the airmatic malfunction with the up arrow. The car will most likely stay at its normal height, but the ride becomes very bouncy once one ADS valve fails.
To fix this problem, you will need to read the codes to determine which ADS valve is faulty, as there are four. One at each air sturt. Then replace the faulty strut along with the ADS valve. The valve itself can not be replaced without replacing the air strut.
Damaged Suspension Airbag
Air springs, on which the whole car sits instead of traditional steel coils, are nothing more than rubber bellows, filled with compressed air. With time, they may become brittle or punctured by dirt buildups and rocks, causing them to leak.
Although the compressor can compensate for this loss to a certain degree, the amount of escaping air will eventually become too large, and the car will sag. But even before that happens, the vehicle might spot the leakage and alert the driver with this warning message. Some air springs come with shock absorbers as one assembly and need to be replaced in pairs.
Faulty valve-block unit
Every AirMatic system has a valve body, which acts as a junction box that directs the air coming from the compressor towards other components. These are pneumatic valves with electrically actuated solenoids that control the airflow.
With time, the O-rings inside the valve body may become brittle or cracked, causing an internal air leak. Other possible failures include defective pressure sensors and malfunctioning solenoids. In most cases, replacing the whole valve body is the only solution.
Severed or blocked airline
All AirMatic components are connected with a series of flexible airlines. As a result of aging or mechanical damage, these plastic hoses may crack or break, letting out the pressurized air.
Depending on where the leak appeared, this may affect just one corner of the car or the whole system.
In addition, the airflow through the hose may be obstructed if it gets jammed or folded during mechanical repairs. Finding the location of the leak can be difficult but repairing the line is usually relatively easy.
Defective Level Sensors
Each end of the vehicle has a sensor that measures the distance between the chassis and suspension. This data is used to determine if the car is leveled and adjust the pressure in each air spring accordingly.
As with any sensor, it can fail for several reasons, including internal electrical shorts and mechanical damage. Also, brackets and linking rods may bend out of shape, giving false readings. In addition, wiring leading up to the sensor and a corresponding connector may be cracked or loose.
Like other electronic systems, AirMatic has several fuses, which protect it from electrical overloads or short circuits. If a fuse blows, it will shut down those components that are wired with it and trigger errors.
Checking for blown fuses is always a good starting point when there are sudden multiple failures.
There is a relay for the air suspension system that can fail. When replacing the air suspension compressor, it is also recommended to replace the air suspension compressor relay.
AirMatic Control Unit
Lastly, the computer or the control device that operates the AirMatic system may also be malfunctioning.
Although this is not that common, it is still worth checking if everything else appears to be working fine. In some cases, the moisture may get into its housing, which causes corrosion and short circuits.
Tests and Diagnostics Tips
- Check operation of air suspension compressor. The compressor needs to generate a certain pressure within a specific time.
- Perform leakage test between valve block and central reservoir.
What does Mercedes-Benz malfunction mean?
It means the air suspension is not working correctly. The vehicle may get stuck raised, or the ride may become very stiff or bouncy. Failure of one of the airmatic suspension components is causing the malfunction and the car symbol + up arrow.
Without reading the codes, determining what is causing the AirMatic malfunction may be difficult. Leaking air struts or broken hoses are easy to spot, as the hissing sounds would give them away, but that's not always the case. The car may drive fine or maybe just a little bouncy in some cases.
In many cases, the suspension malfunction is a bad air compressor, although some other issues may be causing it to stop working, such as a blown a fuse or bad relay. The situation is even more complex with other components, so a suitable diagnostic tool may be needed for tracking down the issue.
Still, you should know that a simple OBD-II scanner will not help here, as these will not have access to the AirMatic control module. Instead, you will need a full diagnostic scanner, such as Mercedes's proprietary Star Diagnostics or similar.
To learn more about how to find out why your Mercedes-Benz is showing suspension malfunction, follow this guide and read the codes from the AirMatic module.
Frequently Asked Questions
Can I drive with a broken AirMatic system?
If the air ride on your Mercedes-Benz is down, it will be sitting on its bump stops. Because these rubber blocks are flexible, you can still drive the car for a few miles, as long as the wheels are not rubbing against anything.
However, the vehicle's suspension geometry and ride quality are affected by this, meaning you should avoid driving it on longer distances.
Do I need to reset the AirMatic system after the repair?
After determining what may be causing the issue, the next step is to replace the faulty compound. With that done, the vehicle's air suspension will usually restore its function. But sometimes, even with that done, the AirMatic still may not work and display a fault message.
If that happens, erasing any stored codes may help. To do so, you will again need a diagnostic tool capable of accessing the Airmatic module.
Warning light with a car and upwards-facing arrow on the dashboard of your Mercedes-Benz is a tell-tale sign of an AirRide issue. This can be caused by anything from a broken compressor or air strut to malfunctionings valve blocks or defective sensors.
In most cases, you will need a suitable diagnostic tool to track down the root of the problem.