2021-2025 Audi A3, S3, RS 3, Q3 DTC U010100 Information

Audi has issued Technical Service Bulletin (TSB) 47 24 30 2074475/2 to address instances of Diagnostic Trouble Code (DTC) U010100, which signifies "Lost Communication with TCM." This TSB, dated July 26, 2024, and superseding an earlier bulletin (47 24-29 dated July 3, 2024), provides crucial information for technicians diagnosing this specific code in various Audi models.

The TSB clarifies that for certain 2021-2025 Audi A3, S3, RS 3, and Q3 vehicles, the presence of the Audi A3 S3 RS3 Q3 DTC U010100 may not indicate an actual problem requiring repair. Instead, it often points to a known software issue within the electromechanical brake servo control unit.

Symptoms

Owners might notice "A warning/indicator lamp is lit up in the instrument cluster." However, the TSB notes that the Audi A3 S3 RS3 Q3 DTC U010100 can also be identified during routine maintenance or inspection without any customer complaint.

Fault Codes / DTCs

The primary fault code addressed by this bulletin is:

Code	Description	Module / Symptom Codes
U010100	Lost Communication with TCM	Electromechanical Brake Servo (Diagnostic Address 23) with symptoms 107008 and/or 108624

This DTC is specifically linked to the electromechanical brake servo control unit, which communicates with the Transmission Control Module (TCM).

Technical Background

The root cause of the DTC U010100 in these specific Audi models is identified as a software issue within the electromechanical brake servo control unit. This issue can trigger the communication fault code without necessarily indicating a hardware malfunction or a drivability concern for the owner.

Important Warnings for Owners and Technicians

This TSB contains critical information regarding the handling of DTC U010100:

• "The DTC U010100 in the A3 8Y with software version 0372 or 0272 or 0307 or 0309 or 0553 and in the Q3 F3 with software version 0372 or 0272 or 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."
• "There must be a different cause for the warning/indicator lamp."

This means that if your vehicle exhibits a warning light, and a scan reveals DTC U010100 with the specified software versions (0372, 0272, 0307, 0309, 0553 for A3 8Y; 0372, 0272, 0207, 0209 for Q3 F3), the code itself should not be the primary focus of repair if there are no other customer complaints. Technicians are instructed to log the permission to ignore this DTC in the ODIS diagnostic system.

Technician Guidance

For technicians encountering the Audi A3 S3 RS3 Q3 DTC U010100 with symptom codes 107008 and/or 108624 (software version 553) in the electromechanical brake servo (diagnostic address 23), the TSB advises that this code can be ignored if there is no customer complaint. If a warning or indicator lamp is illuminated, technicians should investigate other potential causes, as the U010100 code under these specific conditions is not considered the source of a customer-perceptible issue.

Warranty Information

Audi states that this Technical Service Bulletin 2074475 is informational only. It is not applicable to any Audi Warranty claims, as it provides guidance on how to interpret a specific diagnostic code rather than outlining a repair procedure covered by warranty.

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Source: NHTSA ID: 11005893