2023-2025 Audi Air Suspension System Fault C118D01

Owners of various 2023-2025 Audi models, including the Audi e-tron, e-tron Sportback, A6, Q5, Q7, Q8, and others, may encounter an "Air suspension: system fault" message displayed in the instrument cluster. This warning is often accompanied by a specific diagnostic trouble code (DTC) C118D01, which points to an electrical error within the level control compressor system.

Audi Technical Service Bulletin (TSB) 43 24 90 2073034/5 has been released to provide technicians with a diagnostic and repair procedure for this issue. This TSB supersedes an earlier bulletin, Group 43 number 24-88 dated May 7, 2024, incorporating updated warranty information, revised service procedures, and additional model year coverage.

Symptoms

The primary symptom of this issue is the appearance of the message "Air suspension: system fault" in your vehicle's instrument cluster. This indicates a problem with the vehicle's air suspension system, which could affect ride height, comfort, and handling.

Fault Codes / DTCs

When diagnosing the "Air suspension: system fault", technicians will typically find the following diagnostic trouble code (DTC) logged in the suspension control unit -J775- (diagnostic address 0074):

• C118D01: Compressor for level control electrical error.

This specific code helps pinpoint the problem to the electrical components of the air suspension compressor system.

Diagnosis / Trigger Conditions

The TSB specifies that the diagnostic procedure applies if the compressor electronics with part number index A (specifically 4M0.907.778.A) are installed in the vehicle. Technicians will first check the wiring and contacts at both the air compressor and the compressor electronics control unit J1135 for any irregularities.

• If the DTC C118D01 is logged as passive/intermittent and no wiring issues are found, the DTC should be deleted.
• If the DTC C118D01 is logged as active/static and remains active/static even after cycling the ignition off and on, further action is required.
• If the DTC C118D01 is stored a second time in the J775 control unit as passive/intermittent, this also indicates a need for repair.

Repair Procedure Summary

If the diagnostic steps confirm a persistent active/static DTC C118D01 or a recurring passive/intermittent code, the repair involves replacing the control unit for compressor electronics J1135. It is crucial to note that the air compressor itself is generally not replaced for this specific electrical error.

The procedure involves:

1. Verification: Confirming that the compressor electronics part number is 4M0.907.778.A.
2. Inspection: Checking wiring and contacts at the air compressor and compressor electronics J1135.
3. Replacement: If necessary, the control unit for compressor electronics J1135 is replaced. The TSB explicitly states to use part number 4M0.907.778 (without index A) for the replacement part.
4. DTC Clearing: After replacement, any stored DTCs are cleared.

Required Tools or Parts

For this repair, the following parts may be required:

• Control unit for compressor electronics J1135: Part Number 4M0.907.778 (Quantity 01)
• Fasteners, Bolts, Nuts, and Screws: As needed per the repair manual (refer to ETKA/ELSA for specifics).

Important Warnings

Owners and technicians should be aware of the following critical information:

• Do NOT replace the air compressor: The TSB explicitly states to replace the control unit for compressor electronics J1135, not the air compressor itself, for the C118D01 electrical error.
• Applicability: The described procedure only applies if compressor electronics with part number index A (4M0.907.778.A) are fitted in the vehicle.

Warranty Information

This Technical Service Bulletin outlines specific warranty claim types and labor operations for addressing the Audi e-tron air suspension fault C118D01. Warranty coverage is typically available for vehicles up to 48 months or 50,000 miles. For Certified Pre-Owned (CPO) vehicles, G10 claim type applies, requiring owner verification. If the vehicle is outside of any warranty, this TSB serves as informational guidance only.

Service Number: 4316 Damage Code: 0039

Labor Operations:

• Remove and install control unit J1135 (Code: 4316 19xx)
• Charge battery (Code: 2706 8950)
• Diagnostic Time: GFF (Code: 0150 0060, maximum 50 time units)
• Road test prior to and after service procedure: No allowance (0 time units)

All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual.