2017-2025 Audi DTC U140A00 Terminal 30 Fault TSB

Audi has issued Technical Service Bulletin (TSB) 2073867/2, released on May 28, 2025, to provide comprehensive guidance for diagnosing and addressing a specific engine control module issue. This bulletin primarily concerns the illumination of the Malfunction Indicator Lamp (MIL) or exhaust emission lamp in the instrument cluster, which is often accompanied by the storage of Diagnostic Trouble Code (DTC) U140A00. This issue affects various Audi models from model years 2017 through 2025.

The TSB, identified by transaction number 2073867/2, focuses on an interruption in the Terminal 30 voltage supply to the Engine Control Module (ECM), specifically the J623 unit. This condition can lead to operational problems with the engine and trigger error messages within the control modules, specifically noted as "engine -> operation, engine control -> engine control module" and "control modules, services -> error message." Owners experiencing the MIL or exhaust emission lamp warning should be aware of this potential cause for the Audi DTC U140A00.

Symptoms

Owners of affected Audi vehicles, including those from model years 2017-2025, may observe the following symptom:

• The "MIL/exhaust emission lamp lights up in the instrument cluster."

This warning light, commonly known as the Check Engine Light, indicates that the vehicle's onboard diagnostic system has detected a fault related to the engine or emissions system that requires attention.

Fault Codes / DTCs

When the above symptom occurs, technicians performing diagnostics will typically find the following fault codes stored in the Engine Control Module (ECM), which is identified as J623 (address word: 0001):

Code	Description	Module
U140A00	Terminal 30 is stored	ECM
17262	Terminal 30 open circuit	ECM

These codes collectively point to an issue with the Terminal 30 voltage supply. Terminal 30 refers to a constant battery voltage supply, which is critical for the continuous operation and memory functions of the ECM, J623.

Technical Background and Diagnosis

The root cause of the Audi DTC U140A00 is an interruption in the Terminal 30 voltage supply to the ECM, specifically the J623 control unit. This constant power supply is essential for the ECM's proper functioning, including retaining learned values, operating critical engine systems, and ensuring stable control module communication. An interruption can lead to erratic behavior or complete failure of engine control functions, triggering the MIL.

Audi's TSB 2073867/2 emphasizes that Diagnostic Trouble Codes (DTCs) related to this issue may not always be visible during a standard diagnosis session. This can happen if the fault is intermittent or if the codes were previously cleared. In such cases, it is crucial to execute the Guided Fault Finding (GFF) process. This specialized diagnostic procedure is designed to methodically identify the underlying cause of the voltage supply interruption. It is important to note that the DTC should not be cleared without first completing the Guided Fault Finding process, as this could hinder proper diagnosis and make it more difficult to pinpoint the intermittent fault.

Important Warnings for Owners

Audi provides critical instructions for technicians that are also important for owners to understand, particularly regarding the Audi DTC U140A00:

• Do not clear DTCs prematurely: "Do not clear the DTC U140A00 and symptom codes 17262 (Terminal 30 open circuit). The test plan connected to U140A00 should be performed through Guide Fault Finding." Clearing these codes before a thorough diagnosis can obscure the problem and make it harder for technicians to identify the root cause.
• If DTCs are not present: "In some cases, during the repair and maintenance work no DTC is stored in the ECM. This may occur if the DTC has already been clear from a previous diagnosis session. In this case, please work through the relevant test plan 'J623 – Engine Control unit (MDG1) – check terminal 30'." If your vehicle's warning light was on but is now off, the underlying issue may still exist and require specific diagnostic steps to prevent recurrence.

Repair Procedure Summary

The primary repair procedure outlined in Audi TSB 2073867/2 involves performing a comprehensive Guided Fault Finding (GFF) process. This is not a direct repair step but rather a detailed diagnostic sequence that technicians must follow to accurately pinpoint the cause of the Terminal 30 voltage supply interruption to the ECM. The TSB states that "Guide Fault Finding must be performed" in the event of a customer complaint.

Specifically, the process involves performing the "test plan connected to U140A00" through Guide Fault Finding. If no DTC is currently stored in the ECM, technicians are instructed to work through the relevant test plan "J623 – Engine Control unit (MDG1) – check terminal 30." Guided Fault Finding is a structured, software-guided diagnostic approach that helps technicians systematically identify the precise cause of the Terminal 30 interruption. Once the Guided Fault Finding identifies the specific fault, the technician can then proceed with the necessary repairs to restore the constant voltage supply to the ECM, thereby resolving the Audi DTC U140A00.

Warranty Information

For vehicles still under warranty, claims related to this issue should be submitted using specific codes and procedures. The TSB specifies the following details for warranty claims:

• Service Number: 2470
• Damage Code: 0055
• Labor Operations:
  • GFF / Guided Functions (0150 0010) - "See SRT with associated operations"
  • GFF / Guided Functions (0150 0060) - "Time stated on the diagnostic protocol"
• Claim Comment: "As per TSB 2073867/2"

All warranty claims submitted for payment must be in accordance with the Audi Warranty Policies and Procedures Manual. Claims are subject to review or audit by Audi Warranty. If the Guided Fault Finding process does not identify any faults, this service number should still be used. For vehicles outside of warranty, this Technical Service Bulletin is for informational purposes only, meaning any repairs would likely be at the owner's expense.

Owner Action

If you own a 2017-2025 Audi and experience the MIL or exhaust emission lamp illuminating, it is recommended to contact an authorized Audi service center promptly. Inform them about the symptom and mention Audi Technical Service Bulletin 2073867/2. The service center will perform the necessary Guided Fault Finding to accurately diagnose the Audi DTC U140A00 and address the underlying Terminal 30 voltage supply issue to the ECM.

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Source: NHTSA ID: 11018973