The Mercedes-Benz S-Class W221 Airmatic valve block (also known as the Airmatic solenoid valve unit or distribution block) is a crucial component of the Airmatic air suspension system, responsible for distributing and regulating air pressure to the air struts at each wheel. Here is a detailed description:

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Component Name:

Airmatic Valve Block / Valve Unit / Solenoid Valve Block

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Vehicle Application:

Mercedes-Benz S-Class W221 (2006–2013)

Compatible with models equipped with Airmatic suspension (with or without ADS - Adaptive Damping System)

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Function:

• Distributes air from the Airmatic compressor to each individual air spring (front left, front right, rear left, rear right).
• Maintains correct ride height by inflating or deflating each airbag as needed.
• Regulates pressure using internal solenoids and valves.
• Works together with the level sensors, Airmatic control module, and compressor pump.

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Key Features:

• 4 to 6 solenoid valves depending on configuration (some include additional ports for reservoir or axle lift).
• Air inlet/outlet ports with push-fit or threaded connections.
• Mounted typically on or near the air suspension compressor, in the engine bay or near the front axle.
• Common OEM part numbers (may vary by model/year):
  
• A2213200258
• A2213200304
• A2123200358 (shared across some W212 and W221 models)
• 
  

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Common Symptoms of Faulty Valve Block:

• Car sagging on one or more corners after parking
• Slow or failed response to ride height changes
• Compressor running too frequently or for long durations
• Airmatic warning message on dashboard
• Uneven ride height

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Testing/Diagnosis:

• Use Mercedes STAR Diagnosis tool or compatible OBD II scanner to read Airmatic system codes.
• Check for air leaks using soapy water on connections.
• Inspect for internal blockages or solenoid malfunction.

Let me know if you need location diagram, part cross-reference, or replacement procedures.