2023-2024 Audi Air Suspension System Fault DTC C118D01

Owners of certain 2023-2024 Audi models may encounter an "Air suspension: system fault" message in their instrument cluster. This issue is typically accompanied by a specific diagnostic trouble code (DTC) C118D01, indicating an electrical error within the air suspension compressor system. Audi has issued Technical Service Bulletin (TSB) 2073034/4 to provide guidance for diagnosing and resolving this particular problem.

This TSB, identified as 43 24 88 2073034/4, was most recently revised on May 7, 2024, and supersedes previous versions, including TSB 24-87 dated April 11, 2024. The bulletin aims to address the Audi air suspension C118D01 fault by focusing on the compressor electronics.

Symptoms

The primary symptom owners will notice is the warning message "Air suspension: system fault" displayed prominently in the vehicle's instrument cluster. This message directly alerts the driver to a problem with the air suspension system.

Fault Codes / DTCs

When diagnosing the Audi air suspension C118D01 issue, technicians will find the following diagnostic trouble code (DTC) logged in the suspension control unit -J775- (diagnostic address 0074):

• C118D01: Compressor for level control electrical error.

Diagnosis / Trigger Conditions

Diagnosis for the Audi air suspension C118D01 fault begins by verifying if the compressor electronics have part number 4M0.907.778.A. Technicians will then inspect the wiring and contacts at both the air compressor and the compressor electronics J1135 for any irregularities.

If the DTC C118D01 is found to be passive or intermittent, it should be deleted. However, if the DTC is active or static and remains so even after cycling the ignition, further action is required.

Important Warnings

It is crucial to note that if a replacement is necessary, do NOT replace the air compressor itself. The TSB specifically directs technicians to replace only the control unit for compressor electronics J1135. Furthermore, only use the part numbers specified in this TSB, as these include any superseding part numbers.

Repair Procedure Summary

For vehicles exhibiting the Audi air suspension C118D01 fault, the repair procedure outlined in TSB 2073034/4 involves several steps. After checking the wiring and contacts of the air compressor and compressor electronics J1135, if no irregularities are found, the following applies:

1. If the DTC C118D01 is passive/intermittent, the DTC should be deleted.
2. If the DTC C118D01 is active/static and remains active/static after the ignition is switched off and then on again, the control unit for compressor electronics J1135 must be replaced. The air compressor itself should not be replaced.
3. Additionally, if the DTC C118D01 is stored for a second time in the J775 as passive/intermittent, the J1135 control unit should also be replaced.

An improved software for compressor electronics J1135 is planned as a production solution, suggesting that this TSB provides a current fix for existing vehicles.

Required Parts

When replacing the control unit for compressor electronics J1135, the following part is specified:

• 4M0.907.778: Control unit for compressor electronics J1135 (if necessary)

Fasteners, bolts, nuts, and screws should be obtained as needed per the repair manual, typically referenced through ETKA/ELSA.

Warranty Information

Warranty claims for this repair fall under Claim Type 110 for vehicles up to 48 months or 50,000 miles, and G10 for CPO (Certified Pre-Owned) covered vehicles. The Service Number is 4316, with Damage Code 0039. Labor operations for removing and installing control unit J1135 are designated as 4316 19xx. Diagnostic time (GFF) is allocated as 0150 0000. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual.

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Source: NHTSA ID: 11002224