Audi AllRoad Air Suspension Issues Explained(+5 Tips)

In this brief article we are going to discuss the Audi AllRoad 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 AllRoad?

The most common Audi AllRoad Air suspension issues are:

  • Corner Sagging
  • Suspension leaning to one side

How does Audi AllRoad Adaptive suspension work?

The Allroad adaptive suspension was first introduced in 1999 in the A6 Avant as a variant called the A6 AllRoad Quattro. It is now available in the A4 and A6 Allroad Quattro Wagon models, namely the A4 Avant and the A6 Avant.

The Audi Allroad Adaptive Suspension is a system that consists of a pneumatic circuit and Adaptive Dampers all controlled at the same time by the ‘Electronic Chassis Platform’ (ECP). 

The AllRoad Suspension system takes inputs from the 4 corner height sensors, wheel speeds and 

  • adjusts the ride height to 4 -Levels, 
  • Continuously adjusts damping for the active dampers,

depending on vehicle speed and the driver selected mode. 

As an example, at slower speeds, the suspension can be set to the ‘Off-road’ mode, but the moment the speed crosses 40 kmph, the ride height is set one level lower by the ECP.

The drive modes available in the A4 or A6 would vary depending on the generation .

AllRoad Corner Sagging

  • Corner suspension loses ride height after parking
  • In some cases, both sides (left and right) have lost height
  • Explained as seen in the C5(1999 – 2005) AllRoad Quattro

Root Cause:

  • There are 3 potential reasons for ride height loss on parking:
    • Faulty Ride height sensor
    • Air Spring Leakages
    • Valve-Block Defect
    • Faulty Air Compressor
    • Shock Absorber Leakage
  • 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 AllRoad Corner Sagging: Leaking Shock Absorbers

  • The rear Allroad suspension struts have the air spring as well as shock absorber integrated as one assembly. 
  • When the shock absorber fails, oil may not be visible on the outside
  • The leaked shock absorber oil gets into the air lines and creates blockages
  • The oil then stops the compressor from being able to pressurize and lift the air struts

Troubleshooting AllRoad Corner Sagging: Compressor Failure

  • If the compressor ‘humming’ sound can be heard, and the suspension is not able to lift, it could be a case of a failed compressor
  • The Air Compressor tends to corrode over long-term use and internally wears out. Even if the compressor runs, it fails to develop the required pressure.
  • Although it would be best to replace the compressor, you could also purchase a compressor ‘Rebuild Kit’ and attempt to Rebuild the compressor, as explained here in this section.

Troubleshooting AllRoad 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.

Troubleshooting AllRoad 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 AllRoad Corner Sagging: Valve-Block Leakage or Defect

  • The DTC (Diagnostic Trouble Code) will mostly show up as :

“….. – Level Control System…”

  • The AllRoad 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

AllRoad Suspension Leaning to one side

  • The Audi AllRoad 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 the following section.

Calibrating the AllRoad 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

Vehicle Dropping overnight

  • Air suspension warning indication on the dash lights up continuously
  • Air compressor not working because of the suspension
  • Suspension cannot be lifted or raised
  • Explained as observed on the A6 Allroad Quattro

Troubleshooting Vehicle Dropping: Electrical Fault

  • It be best to Diagnose the errors using a Scanner diagnostic Tool
  • If the Fault Code  “31-10 – Open or Short to Ground – Intermittent” shows, it could be an electrical connector fault
  • Remove and Check the Valve Block connector terminals for corrosion and clean if necessary
  • If the Fault Code  “01769 – Sensor for vehicle leveling front right (G289)” shows, you can check the electrical continuity at the height sensor connector first.
  • If needed, replace the particular faulty corner height sensor

Tips on Replacing the Air Springs on an Audi AllRoad

  • 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.

Pro-Tip:

  • 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.

Conclusion

In this brief article we have discussed the different Audi AllRoad Air Suspension problems, what the causes are, and how these issues could be effectively dealt with.

References 

Audi MediaCenter Model Updates Official Page

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