2021-2024 Audi Q7/Q8/SQ7/SQ8/RS Q8 Rear Suspension Lowering Issue

Owners of certain Audi models may encounter a situation where the rear suspension lowering function does not work consistently. This issue, identified by Audi Technical Service Bulletin (TSB) 43 23 77 2059841/4, affects a range of vehicles, including the 2021-2024 Audi Q7, Q8, SQ7, SQ8, and RS Q8. The TSB clarifies that the problem is usually not due to a faulty component but rather how the system is used.

Symptoms

If you own a 2021-2024 Audi Q7, Q8, SQ7, SQ8, or RS Q8, you might notice that the rear suspension lowering is intermittently not available. This means that when you attempt to lower the rear suspension, the function may not activate as expected, or it might work sometimes but not others. This can be an inconvenience, especially when loading or unloading cargo.

Fault Codes / DTCs

When this intermittent issue occurs, a technician inspecting the vehicle may find specific Diagnostic Trouble Codes (DTCs) logged in the suspension control module, designated as J775 (address word 0074). These codes indicate specific conditions related to the lowering button:

Code	Description
C11B515	Button for high load level, interruption/short circuit to positive
C11B615	Button for low load level, interruption/short circuit to positive

These DTCs point to an electrical signal interruption or short circuit related to the buttons used to control the rear suspension's high and low load levels. They are crucial for diagnosing the Audi Q8 rear suspension lowering problem.

Diagnosis / Trigger Conditions

The technical background provided by Audi indicates that the primary cause for the rear suspension lowering being intermittently unavailable is the unintentional operation of the lowering button while driving. This can happen if objects in the trunk area accidentally press the button, leading the system to register an unexpected input. The suspension control module, J775, then logs the corresponding DTCs (C11B515 or C11B615) as a result of this unintended activation.

Important Warnings

Audi's TSB 43 23 77 2059841/4 includes a critical note for technicians and owners alike. It explicitly states: “Do not replace the J775 or the button for the rear suspension lowering or any other component in the vehicle.” This warning is vital as it prevents unnecessary and costly part replacements. The issue is not a hardware failure but rather a functional characteristic related to how the system interprets inputs.

Repair Procedure Summary

Given that the issue is not a component failure, the recommended service procedure focuses on customer education rather than repair. Technicians are instructed to explain the functionality of the rear suspension lowering system to the customer. This explanation should include the possibility of the button being unintentionally operated while driving, for example, by items shifting in the trunk. Understanding this behavior can help owners avoid the intermittent unavailability of the Audi Q8 rear suspension lowering feature.

Owner Action

If you experience your 2021-2024 Audi Q7, Q8, SQ7, SQ8, or RS Q8's rear suspension lowering becoming intermittently unavailable, and especially if you've seen the check engine light or had DTCs C11B515 or C11B615 diagnosed, it's important to understand the nature of this issue. There is no component replacement required. Instead, ensure that the rear suspension lowering button is not accidentally pressed by cargo or other items in the trunk while the vehicle is in motion. If the problem persists or you have concerns, consult with an authorized Audi service center.

This bulletin, 43 23 77 2059841/4, supersedes Technical Service Bulletin Group 43 number 22-67 dated August 3, 2022, and was last revised on June 1, 2023.

Source: NHTSA ID 10238164