The 2000-2006 Mercedes S430 is built with the following suspension components:
2000-2006 Mercedes S430 Air Struts (x4)- (models with air suspension only). Commonly referred to as air bags, a plastic and rubber spring uses pressurized air as a cushion (in place of a metal coil spring) to support the weight of the vehicle. On vehicles with the air suspension systems, an air spring is mounting atop a traditional passive strut filled with a gas-charged hydraulic fluid at each corner of the vehicle. The entire unit is commonly known as an air strut. The rubber portion of the air springs are the number one cause of all air suspension leaks. Since all air springs go bad at about the same rate, if one is leaking, the others will not be far behind. For a proper repair, all of them need to be replaced at the same time.
2000-2006 Mercedes S430 Active Hydraulic Strut (x4)- (models with hydraulic active suspension). Vehicles with the Active Body Control (ABC) active hydraulic suspension will have one of these on each wheel. These struts are more expensive and more complicated than a traditional passive strut because they have mechanisms which change the dampening rate (valving) inside of the strut hundreds of a times a minute. Hydraulic fluid is delivered to each strut at a much higher rate of pressure than a traditional strut. The dampening rates are controlled by a suspension control module.
2000-2006 Mercedes S430 Height Sensors (x4)- a linkage located near each wheel of the vehicle that constantly measures the height of the vehicle and reports this information back to the control module so that the computer can identify if changes in height need to be adjusted accordingly. The ride height sensor is a moving part, and like all moving parts, they will eventually wear out.
2000-2006 Mercedes S430 Air/Hydraulic Lines- tubes that run from a compressor to the air struts (or a hydraulic pump to the hydraulic struts for models with hydraulic active suspension), which deliver air to the air springs or hydraulic fluid to the active struts in order to adjust the height of the vehicle.
2000-2006 Mercedes S430 Solenoids (x4)- These plastic and metal components regulate the air pressure for each air spring. Solenoids start to leak as they wear out and may cause the vehicle to sag or to lean. This will cause the ride height sensor to send a signal to activate the compressor in an attempt to inflate the air suspension and level out the vehicle. This excessive work load will eventually lead to total failure of the compressor.
2000-2006 Mercedes S430 Compressor Assembly- (models with air suspension only). Creates and sends pressurized air to the air springs. When the air suspension starts leaking, the compressor (also known as an air pump) starts working harder to try to keep the system inflated. By the time air suspension leaks down completely, the compressor will either have failed or be well on its way to full failure.
2000-2006 Mercedes S430 Hydraulic Pump- if your Mercedes has hydraulic suspension instead of air suspension, then the hydraulic steering pump will also serve as the reservoir for the hydraulic fluid going into the struts.
2000-2006 Mercedes S430 Suspension Control Module- a computer which is responsible for the operations of the air suspension system (or ABC active hydraulic system) and maintaining the vehicle's correct ride height.
2000-2006 Mercedes S430 Rubber O-rings- Although they are the least expensive parts of the active suspension systems, they are responsible for maintaining the seal where all of the air lines or hydraulic lines connect. Be sure to replace the rubber O-rings when repairing any active suspension system.