2023-2025 Audi Air Suspension Fault C118D01 TSB

Owners of certain 2023-2025 Audi models may encounter an "Air suspension: system fault" message displayed in the instrument cluster. This warning is often accompanied by the air spring symbol lighting up, indicating a problem with the vehicle's adaptive air suspension system. The underlying cause is frequently identified by the diagnostic trouble code (DTC) C118D01, which points to an electrical malfunction in the compressor for the level control system.

This technical service bulletin, identified as 2073034/8, provides guidance for diagnosing and resolving the Audi air suspension fault C118D01.

Symptoms

If your Audi is affected by this issue, you may observe the following:

• The message "Air suspension: system fault" appears in the instrument cluster.
• The air spring symbol lights up on the dashboard.
• The vehicle's damping/suspension regulation may not function correctly, or its operation sequence might be incorrect.
• The level control system, pitch, and roll compensation may not function as expected.

Fault Codes / DTCs

When scanned, the suspension control unit (-J775-) will log the following diagnostic trouble code:

Diagnostic Address	Diagnostic Trouble Code	Fault Symptom	Storage State
0074 - Chassis control	C118D01	Compressor for level control system Electrical malfunction	static
0074 - Chassis control	C118D01	Compressor for level control system Electrical malfunction	intermittent

Diagnosis / Trigger Conditions

The presence of DTC C118D01 in the suspension control unit -J775- confirms the electrical malfunction. Technicians should first check the wiring and contacts at the air compressor and the compressor electronics control unit (-J1135-). If no irregularities are found with the connections, the repair procedure outlined in TSB 2073034/8 should be followed.

Important Warnings

Audi emphasizes that the repair described in this bulletin must only be performed if all specified criteria (including model/type, chassis number, engine/motor, gearbox code, PR number(s), part number, and software version) are met exactly. Failure to adhere to these criteria may result in the solution not resolving the problem, leading to repeat repairs. In such cases, Audi may reject warranty claims and charge back the cost of parts. Specifically, the bulletin states:

• Do NOT replace the air compressor itself. The issue lies with the control unit for compressor electronics -J1135-.

Repair Procedure Summary

The primary repair for the Audi air suspension fault C118D01 involves replacing the control unit for compressor electronics.

1. Initial Inspection: Verify the customer complaint and confirm the presence of DTC C118D01.
2. Wiring Check: Inspect the wiring and contacts connected to the air compressor and the compressor electronics control unit (-J1135-).
3. Component Replacement: If the wiring and contacts are found to be in order, replace the control unit for compressor electronics -J1135-. It is crucial to replace only this control unit, not the entire air compressor.
4. Post-Repair Test: Perform a road test after the service procedure to ensure the issue is resolved.

Required Parts

To resolve the Audi air suspension fault C118D01, the following part is required:

• Control unit for compressor electronics J1135: Part Number 4M0.907.778

Additional fasteners, bolts, nuts, and screws may be needed as per the repair manual and can be identified via ETKA.

Owner Action

If your 2023-2025 Audi displays the "Air suspension: system fault" message or you suspect an Audi air suspension fault C118D01, it is recommended to schedule an appointment with an authorized Audi service center. The diagnostic trouble code C118D01 will help technicians pinpoint the issue quickly. This repair is covered under warranty if your vehicle meets the specific criteria outlined in the TSB. If the vehicle is outside of any warranty, this Technical Service Bulletin is informational only.

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Source: NHTSA ID: 11016527, Transaction No.: 2073034/8