The 2000-2005 Audi (C5) Allroad Quattro is built with the following suspension components:
2000-2005 Audi (C5) Allroad Quattro Air Struts (x4)- Metal tubes filled with a gas-charged hydraulic fluid that controls bouncing motions and dampens vibration caused by travel on rough road surfaces.
On this vehicle, the struts are the mounting place for an air springs that fills with compressed air and helps support the weight of the vehicle. These air springs, which take the place of a traditional steel coil spring, are managed by the suspension control module. The air springs are made of plastic and rubber and eventually develop cracks in the rubber and leak air from the system. The entire air strut unit can cost as much as $1458 each for Original Equipment units at the Audi dealer.
2000-2005 Audi (C5) Allroad Quattro Air Lines- Tubes that carry pressurized air from the air compressor to the rubber air springs.
2000-2005 Audi (C5) Allroad Quattro Solenoids (x4)- Plastic and metal components that regulate the air pressure for each air spring. Solenoids start to leak as they wear out, causing the compressor to run excessively. Leaking solenoids contribute to failure of the compressor.
2000-2005 Audi (C5) Allroad Quattro Air Compressor- Creates and sends pressurized air to each of the vehicle's four air struts. 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 has completely failed or will no longer make enough air to keep the system inflated. An Original Equipment compressor can cost as much as $1430 at the Audi dealer. It is recommended to at the very least replace all four air struts at the same time as replacing the compressor.
2000-2005 Audi (C5) Allroad Quattro Dryer Assembly- Used to keep moisture out of air lines and air springs in order to prevent freezing and internal cracking of these parts. Once air suspension starts leaking, moisture will build-up throughout the air system. Moisture damages the air suspension from the inside. The dryer will need to be replaced in order to eliminate the moisture and prevent any further damage.
2000-2005 Audi (C5) Allroad Quattro Suspension Control Module- A computer responsible for the operations of the air suspension system and maintaining the vehicle's correct ride height. Replacement of this module at the dealer can cost as much as $975.
2000-2005 Audi (C5) Allroad Quattro Rubber O-rings- Although they are the least expensive parts of the air suspension, they are responsible for maintaining the seal where all of the air lines connect. Be sure to replace the O-rings when repairing any air suspension system.