2021-2024 Audi U010100 Lost Communication with TCM TSB

Audi Technical Service Bulletin (TSB) 2074475/1, issued on July 3, 2024, addresses a specific diagnostic trouble code (DTC) U010100. This TSB provides crucial information for technicians and owners regarding instances of "Lost Communication with TCM" in the electromechanical brake servo system of various Audi models. The bulletin clarifies that under certain conditions, this particular fault code does not indicate an actual problem requiring repair.

Symptoms

Owners of affected Audi vehicles may experience one of two primary conditions related to this TSB:

• A "warning/indicator lamp is lit up in the instrument cluster." This is a direct visual alert to the driver.
• During routine maintenance or inspection, the DTC U010100 with symptom 107008 is identified, even if there is no noticeable customer complaint or warning light.

Fault Codes / DTCs

The primary diagnostic trouble code addressed by this bulletin is:

• U010100: Lost Communication with TCM (Transmission Control Module)
  • Associated symptom code: 107008
  • Identified in diagnostic address 23 (electromechanical brake servo)

Technical Background

The root cause of the DTC U010100 being recorded in the electromechanical brake servo is a software issue within the electromechanical brake servo control unit. This software anomaly can lead to the logging of the "Lost Communication with TCM" fault without an actual communication failure or operational impact.

Important Warnings

Audi TSB 2074475/1 provides a critical directive for technicians and owners:

• The DTC U010100 in the Audi A3 8Y with software versions 0372, 0272, 0307, or 0309, and in the Audi Q3 F3 with software versions 0372, 0272, 0207, or 0209 in the electromechanical brake servo does not lead to a customer complaint and can be ignored. Permission to ignore must be logged in ODIS for this DTC.
• If a "warning/indicator lamp is lit up in the instrument cluster" is present, there must be a different underlying cause for the warning, as the U010100 code in these specific software versions is not the reason.

What Owners Should Know

If you own a 2021-2024 Audi A3, S3, RS 3, or Q3 and encounter the Audi U010100 TCM fault code, especially if it's detected during service without any noticeable symptoms or warning lights, it's important to be aware of this TSB. The bulletin clarifies that for specific software versions in the electromechanical brake servo, this code is benign and should not trigger unnecessary repairs. This TSB is informational only and is not applicable to any Audi Warranty, meaning any diagnostic work or repairs performed outside the scope of this guidance would typically not be covered under warranty.

If you see a "warning/indicator lamp is lit up in the instrument cluster," and your vehicle's software matches the versions mentioned in TSB 2074475/1, the warning is likely due to another issue. It is recommended to have your vehicle diagnosed by an authorized Audi service center to identify the actual cause of any active warning lights.