2023-2024 Audi Air Suspension System Fault DTC C118D01

Symptoms

Owners of certain 2023-2024 Audi models, including the Audi e-tron, may observe a specific warning message in their instrument cluster. The primary symptom is the message "Air suspension: system fault" displayed to the driver. This indicates a problem with the vehicle's air suspension system, which can affect ride height and comfort.

Fault Codes / DTCs

When the "Air suspension: system fault" message appears, technicians will typically find a specific Diagnostic Trouble Code (DTC) logged in the suspension control unit (-J775-, diagnostic address 0074). The relevant DTC for this issue is:

Code	Description
C118D01	Compressor for level control electrical error

This C118D01 code points directly to an electrical problem with the compressor responsible for managing the air suspension's level control.

Diagnosis / Trigger Conditions

Diagnosis for the Audi e-tron air suspension fault begins by checking the wiring and contacts at both the air compressor and the compressor electronics control unit J1135. If these components show no irregularities, further steps depend on the nature of the DTC C118D01.

If the DTC C118D01 is logged as passive/intermittent, meaning it occurred temporarily, the initial step is to delete the DTC. However, if the DTC is logged as active/static and remains active/static even after cycling the ignition off and on, it indicates a persistent problem. Additionally, if a passive/intermittent C118D01 code reappears a second time in the J775 control unit, it also points to a more significant issue.

Repair Procedure Summary

For vehicles exhibiting the persistent Audi e-tron air suspension fault or a recurring passive/intermittent DTC C118D01, the repair involves replacing the control unit for compressor electronics J1135. It is crucial to replace the control unit itself, not the entire air compressor, as specified in Technical Service Bulletin 43 24 88 2073034/4.

This procedure applies specifically if the vehicle is fitted with compressor electronics having part number index A (affected part number 4M0.907.778.A). The TSB notes that improved software for the compressor electronics J1135 is planned, but the current repair involves hardware replacement.

Required Parts

To address the C118D01 fault, the following part may be required:

• Control unit for compressor electronics J1135: Part number 4M0.907.778 (without index A). Fasteners, bolts, nuts, and screws should be obtained as needed per the repair manual.

Warranty Information

This Technical Service Bulletin 43 24 88 2073034/4 outlines specific warranty claim procedures. The claim type covers vehicles up to 48 months or 50,000 miles, and G10 for Audi Certified Pre-Owned (CPO) vehicles. If a vehicle is outside of warranty, this bulletin serves as informational guidance. The service number for this procedure is 4316, with a damage code of 0039. Labor operations for removing and installing the control unit J1135 are coded as 4316 19xx, and diagnostic time is GFF (0150 0000).

Important Warnings

Owners and technicians should note that if the DTC C118D01 is active/static, or if it reappears as passive/intermittent, the correct component to replace is the control unit for compressor electronics J1135, not the air compressor itself. Replacing the air compressor will not resolve the underlying electrical error in the control unit.

NHTSA ID

11002124