Air Spring/Air Bag

Replace the air spring/air bag on a 2007-2013 Mercedes-Benz S65 AMG equipped with AIRMATIC suspension. This procedure involves removing the wheel, disconnecting electrical connections, and replacing the pneumatic strut assembly.

Warnings

Tools required

Parts

• Air spring/strut assembly (AIRMATIC) × 1 — Use OEM specification - A221 320 XX XX (front) or A221 320 XX XX (rear)
• Air spring O-ring seal × 1 — Use OEM specification
• Strut tower mounting hardware (if corroded) × 1 — Use OEM specification

Preparation

1. Connect Mercedes-Benz STAR diagnostic tool or compatible scanner to vehicle
2. Navigate to AIRMATIC control module and activate 'Transport Mode' or 'Service Mode' to depressurize the air suspension system
3. Allow 2-3 minutes for complete system depressurization
4. Park vehicle on level surface and engage parking brake
5. Loosen wheel lug nuts while vehicle is on ground
6. Raise vehicle using lift or floor jack and support securely on jack stands at manufacturer-specified lift points
7. Remove wheel completely
8. Verify the air line pressure is released by carefully pressing on the air line connector

Procedure

1. 1

   Remove wheel and access air spring
   With the vehicle properly supported, remove the wheel completely. Inspect the wheel well liner and remove any clips or fasteners blocking access to the air spring upper mount. On some models, you may need to partially remove or fold back the wheel well liner.
2. 2

   Disconnect air supply line
   Locate the air supply line connected to the air spring (typically near the bottom or mid-section of the strut). Press the release collar on the quick-connect fitting and carefully pull the air line straight out. Inspect the O-ring on the air spring fitting for damage. Cap or cover the air line to prevent contamination.
   ⚠If any air pressure is still present, stop immediately and re-verify system depressurization using the diagnostic tool.
3. 3

   Disconnect electrical connections
   Locate the electrical connector for the air spring level sensor and/or damper adjustment (if equipped with Adaptive Damping System). Press the release tab and disconnect the connector. On models with ADS, disconnect the damper control connector from the strut assembly.
4. 4

   Remove lower mounting hardware
   Locate the lower strut mounting bolts that attach the air spring assembly to the wheel hub or control arm. Apply penetrating oil if necessary. Remove the lower strut bolts completely. Support the strut assembly by hand to prevent it from falling.
   ⚠The air spring assembly will be free to move once lower bolts are removed. Support it manually or with a strap to prevent damage.
   Torque spec

   Strut Bolts156 Nm (115 lb-ft)
5. 5

   Access upper strut tower mounting
   Open the trunk (for rear) or hood (for front). Locate the strut tower access cover - on rear applications, this may be behind interior trim panels in the trunk. Remove the protective cap or cover to expose the upper strut mounting nuts. Front struts are typically accessible from the engine bay near the fender.
6. 6

   Remove upper strut tower nuts
   While supporting the air spring assembly from below, remove the upper strut tower mounting nuts. Typically there are three nuts securing the strut mount to the chassis. Keep the mounting hardware organized for reinstallation. Once all nuts are removed, carefully lower the air spring assembly from the wheel well.
   Torque spec

   Strut Tower Nuts50 Nm (37 lb-ft)
7. 7

   Inspect and prepare new air spring
   Remove the new air spring from packaging. Compare with the old unit to verify correct application. Inspect the air line connection fitting and ensure the O-ring is properly seated. If the level sensor or damper adjustment module transfers from the old unit, carefully remove it using the appropriate tools and install on the new air spring. Ensure all electrical connectors are clean and undamaged.
8. 8

   Install new air spring assembly
   Guide the new air spring assembly into position through the wheel well. Align the upper mounting studs with the holes in the strut tower. Thread the upper strut tower nuts onto the studs by hand, but do not fully tighten yet. Ensure the strut mount is properly seated and oriented correctly.
9. 9

   Secure upper mounting
   Torque the upper strut tower mounting nuts to specification in a star pattern to ensure even loading of the strut mount. Verify the strut mount rubber is not pinched or twisted.
   Torque spec

   Strut Tower Nuts50 Nm (37 lb-ft)
10. 10

    Secure lower mounting
    Align the lower portion of the air spring assembly with the mounting points on the wheel hub or control arm. Install the lower strut mounting bolts and torque to specification. Ensure the strut is properly positioned and not binding.
    Torque spec

    Strut Bolts156 Nm (115 lb-ft)
11. 11

    Reconnect electrical and air connections
    Reconnect the electrical connector to the level sensor and/or damper adjustment module until it clicks into place. Connect the air supply line to the air spring fitting by pushing it straight in until it seats with an audible click. Gently tug on the line to verify it is locked in place.
12. 12

    Reinstall wheel and lower vehicle
    Reinstall any wheel well liner components that were removed. Mount the wheel and hand-thread all lug nuts. Lower the vehicle until the tire just contacts the ground but does not bear full weight. Torque the wheel lug nuts in a star pattern to specification. Fully lower the vehicle and remove jack stands.
    Torque spec

    Wheel Lug Nuts183 Nm (135 lb-ft)
13. 13

    Reactivate AIRMATIC system and calibrate
    Using the diagnostic tool, exit Transport/Service Mode to reactivate the AIRMATIC system. The system will automatically begin to inflate the air springs. Monitor the inflation process and watch for any air leaks at the connections. Perform a level sensor calibration procedure using the diagnostic tool. This typically involves raising and lowering the suspension through its full range of motion.
    ℹ️The vehicle may need to run for several minutes for the suspension to reach normal operating height. This is normal during initial pressurization.

Reassembly

1. Reinstall all trim panels, covers, and protective caps that were removed
2. Clear any diagnostic trouble codes that may have been stored during the repair
3. Verify suspension height is correct and even side-to-side using the diagnostic tool or visual inspection

Verification

• Start the engine and allow the AIRMATIC system to fully pressurize - verify the vehicle rises to normal ride height within 60 seconds
• Use the diagnostic tool to verify no fault codes are present in the AIRMATIC control module
• Visually inspect all air line connections for leaks by applying soapy water and watching for bubbles
• Test drive the vehicle and verify normal suspension operation, listening for any unusual noises
• Verify level sensor operation by using the diagnostic tool to adjust ride height and confirming the vehicle responds correctly
• After test drive, re-inspect air spring connections for any signs of leakage or looseness
• Verify wheel lug nut torque after 50-100 miles of driving

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle