How to Test Mercedes Benz Suspension Air Compressor

This guide provides instructions on how to diagnose a Mercedes Benz's Airmatic (suspension) compressor.

If your Mercedes is equipped with an Airmatic suspension system and suddenly you have a feeling that your car sits lower than usual, then you probably have a faulty air suspension compressor. 

What you will need

Symptoms

One of the symptoms of a bad airmatic suspension compressor is the unusual low height of your car on all four wheels The problem may not always be the air compressor, but you have to isolate the air compressor first.

Procedure

  1. Get a hold of a professional scanner.
  2. Park the car on a flat surface and set your parking brake on.
  3. Locate the OBD-II port. To find the OBD-II port, open the drivers' side door, look under the dash; you will find it next to the red hood release lever.
  4. Pull the cover down and plug in your OBD-II scanner.
  5. Shift the vehicle in park. In some models, you have to start the engine so that the air suspension module would go online. On other models, turning the ignition on would suffice.
  6. Depending on the scanner, you may need to choose the make of the car, navigate to the system menu, go to chassis then suspension. The most important step is to read the suspension fault codes.
  7. If the scanner reports an error similar to "Recovery time to fill a central reservoir is too long," the code's status is current or current and stored. Then the problem is that the air compressor is working too hard to fill the central air reservoir with a recommended pressure of 13-16 bar. 
  8. To verify if the compressor is faulty, again depending on the scanner, there would be some other menu before you could get to the Pneumatic Test. In the Pneumatic Test, choose Airmatic Control Unit. This command will open the Airmatic relief valve on the air compressor for forty seconds to release air from the suspension. The compressor will turn on for forty seconds while the pressure sensor is measuring the air pressure. If the compressor fails to fill the tank with 16 bar within forty seconds, then the fault will be stored again, and definitely, your air compressor has a problem and needs replacement.  

Frequently Asked Questions

What is a central airmatic reservoir?

  • The central reservoir is a metal pressure vessel that stores compressed air at 13-16 bar and levels the vehicle. This tank is incorporated to reduce the dependency on the air compressor and to reduce noise. The tank is most commonly used to level the vehicle when the door or trunk is first opened. 

What are the components of the Airmatic suspension system?

  • Airmatic Control Module
  • Instrument Cluster
  • Level and Damping Control Switch
  • Level Sensors
  • Valve Block Assembly
  • Main Reservoir
  • Strut & Damper Assembly
  • Air Springs
  • Rear Axle Distribution Block

What is the lifespan of a Mercedes Benz Airmatic compressor?

  • You have to replace it every 125,000 miles.

Vehicle Applications

Mercedes-Benz E-Class (W211)

  • E500: Model years 2003-2006
  • E550: Model years 2007-2009
  • E55: Model years 2003-2006
  • E63: Model years 2007-2009

Mercedes-Benz CLS-Class (W219)

  • CLS500: Model year 2006
  • CLS55: Model year 2006
  • CLS550: Model years 2007-2011
  • CLS63: Model years 2007-2011


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How to Test Mercedes Benz Suspension Air Compressor If your Mercedes is equipped with an Airmatic suspension system and suddenly you have a feeling that your car sits lower than usual, then you probably have a faulty air suspension compressor.