In this brief article we are going to discuss the Audi A6 Air Suspension problems, what the causes are, and how these issues can be effectively dealt with.
What are the common air suspension issues in an Audi A6?
The most common Audi A6 Air suspension issues are:
- A6 Corner Sagging
- A6 Suspension leaning to one side
How does Audi A6 Adaptive suspension work?
The Audi A6 Adaptive Suspension is a system that controls the Air suspension ride height and the Damper’s damping rate using solenoid control along with the help of accelerometers and ride height sensors.
Adaptive air suspension is fitted to the 50 TDI and 55 TFSI in Vorsprung trim. The Audi A6 40 and 45 Vorsprung models get adaptive suspension but with only coil Springs.
The A6 air suspension system consists of air struts at 4 corners, an air compressor, an air tank reservoir/accumulator, a solenoid valve block to distribute air pressure to the struts, and a control system to manage all of these.
Although the A6 Adaptive suspension Control interface would look different from other Volkswagen group air suspensions, the A6 air suspension system works almost the same like the Audi Q7, the VW Touareg, the Porsche Cayenne and the Porsche Panamera.
A6 Corner Sagging
- Corner suspension loses ride height after parking
- In some cases, both sides (left and right) have lost height
- Raise / Lower Option not shown in the Display Menu
- There are 3 potential reasons for ride height loss on parking:
- Faulty Ride height sensor
- Air Spring Leakages
- Valve-Block Defect
- Air leakage related suspension sagging generally is seen when the car is parked overnight and sometimes even over a period of days.
- This fault can be confirmed using the VCDS Scanning/Diagnosis tool
- Before starting the scan clear all Fault codes that have already been stored
- Start the vehicle and try to lift the vehicle by selecting “Lift” option
Troubleshooting A6 Corner Sagging: Ride Height Sensor Linkage
- You need to Scan the Fault codes with the Ignition ON
- Error codes like “Level Control system sensor : Mechanical malfunction” point to the ride height sensor linkage as a probable issue.
- The faulty linkages need to be corrected or replaced.
- Once the linkages have been rectified the “Air susp.: Wheel change” needs to be changed back to OFF
- Visually inspect if there is a difference in height between the left and right side in the front and the back
- Any difference in height can be corrected by doing a height calibration. The steps to do a height calibration are explained in this section.
- Before lifting the vehicle for suspension work, especially for Audi with Adaptive Air, the ride height sensors get disturbed and tend to throw errors when the car is back on the ground. Therefore, you need to set the “Air susp.: Wheel change” to ON under the ‘Service and Checks’ Menu in the Center Console.
Troubleshooting A6 Corner Sagging: Air Spring Leakage
- If the Ride height sensor linkages were not the issue, the next most probable cause would be an air leakage somewhere in the air suspension air circuit.
- In the case of air leakages, the system does often detect and display the error code.
- But, however, there have been many cases where confirmed leakages were not detected by Diagnostics.
- Air springs are known to wear out and crack at the rubber bellow surface gradually after accumulating mileage. They generally would last 70K to 80K miles depending on usage.
- In a high mileage vehicle, the air springs would be the first place to check for leakages.
- Fill the Air springs by either
- Turning ON the ignition, or
- In the Diagnostic tool, use the “Air Filling/Venting Set-up” Inspection/Test to fill air into the system, OR
- If the diagnostic method is not possible, then you can pressurize the air spring through the inlet using an external air compressor
- Once the air springs are inflated, you need to spray springs with soap solution to check for leaking.
- After spraying the soapy water solution, wait to see if there are white foam bubbles that stay at one spot even after wiping it with a finger.
- In cases where the leak is major, you even hear a hissing noise coming from the leakage point and be able to locate it by ear.
- Once you have confirmed that there indeed is a leak, the air spring has to be replaced. Read this section to know tips on how to easily replace your Audi air spring.
Troubleshooting A6 Corner Sagging: Valve-Block Leakage or Defect
- The DTC (Diagnostic Trouble Code) will mostly show up as :
“C104600 – Level Control System…”
- The A6 Valve block is located in the boot next to the spare wheel
- Use a soapy water spray to detect bubbles at the valve block air connector fittings
- If there is a crack or damage at the valve block body, then it will need to be replaced.
- Suppose there were no cracks/damages or leakages, then you need to check whether the valve is properly sending air to the individual air struts. This can be done using the diagnostic tool
A6 Suspension Leaning to one side
- The Audi A6 Air Suspension, sometimes, makes the car lean to one side due to daily use and wear in the suspension. But at the same time the suspension is not fully sagging.
- The Self-adjust mechanism of the suspension does not Level the car Flat, or in other words, one side (either left or right)
- Ride height is self-adjusted by the Suspension System at a different ride height at one corner, compared to the opposite side.
- This sort of difference in ride height can be corrected by doing a height calibration. The steps to do a height calibration are explained in this section.
Calibrating the A6 Adaptive Air Suspension
- You can solve the Leaning Problem using a Diagnostic Tool that you plug into the OBD 2.
- In VCDS Select ‘Control Module’ ->” Level Control” – “Options” -> “Security Access” and then “Adaptation”
- In order to access the Adaptation (calibration) module, you will need to enter the access code of the vehicle
- You will need to input the 4 corners’ Ride Height in the software starting by entering “01” as the ‘Channel number’ for the ‘Front Left’ suspension and then clicking ‘Read’
- The diagnostics shows the reference (factory set) values at each corner
- You will need to input the actual ride height values at each Channel (corner) measuring from the wheel center to the bottom of the fender in the vertical direction
- It then runs a program which will self calibrate and correct the ride heights at each corner to the factory set values
Tips on Replacing the Air Springs on an Audi A6
- Before removing the air spring for replacement, be sure to relieve the air pressure from it at the valve block, which is located in the underbody near the rear bumper.
- Relieve the left or right air spring valve by loosening the connector gradually. If this is done suddenly, then you could risk damaging the O-rings within the air connector fitting.
- While replacing the Air Spring, be sure to cut off the portion of the line that was squeezed or stretched in the old fitting after disconnecting. The reason being that the old used portion of the air line could crack and cause a potential leak.
- Some aftermarket brand replacement bellows tend to give a higher service life as compare to the original OE spare part
- Moreover, some aftermarket replacement parts also come with a lifetime warranty instead of a limited warranty offered by manufacturer
Tips on Rebuilding the Air Suspension Compressor
- This applies to air suspension from all generations
- To check for compressor issues, you need to dismantle it and check the Piston, Cylinder and Piston ring condition.
- The best course of action would be to replace the compressor, but for economic reasons, you could also try using a repair kit (Piston rings and 2 o-rings) to rebuild the compressor.
The rebuild option does come with risks as there could be issues in the compressor other than just the piston and rings.
In this brief article we have discussed the different Audi A6 Air Suspension problems, what the causes are, and how these issues could be effectively dealt with.
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