2023-2025 Audi Ignition Fault: DTC U014100 / U043100 TSB

Symptoms

Owners may experience a critical issue where the "Ignition cannot be switched on." This prevents the vehicle from starting or being operated. This symptom is often linked to specific diagnostic trouble codes (DTCs) stored in the vehicle's gateway module.

Fault Codes / DTCs

When the "Ignition cannot be switched on" symptom occurs, technicians may find the following diagnostic trouble codes (DTCs) stored in the Data Bus On Board Diagnostic Interface -J533- (address word 0019):

Code	Description
U014100	Lost Communication With Body Control Module "A"
U043100	Invalid Data Received From Body Control Module “A”

Additionally, after the repair procedure, a DTC C115E54 for "Inertial sensors no basic setting" may be stored in the Airbag Control Unit, -J234- (address 0015).

Diagnosis / Trigger Conditions

The root cause for the ignition issue and the associated DTCs U014100 and U043100 is identified as outdated software within the Comfort System Central Control Module, J393 (diagnostic address 0046). The presence of these specific DTCs in the gateway module confirms the need for a software update.

Repair Procedure Summary

To resolve the issue of the ignition not being able to be switched on, a software update for the Comfort System Central Control Module, J393 (address 0046) is required. The repair process involves several key steps:

1. Preparation: Before flashing the Comfort System Central Control Module, J393, technicians must reset terminal 30 by pulling the relevant fuses. The latest wiring diagrams should be consulted to locate these fuses accurately.
2. Software Update: The J393 module must be updated using the SVM action code 46A034. This process should follow the instructions detailed in TSB 2011732, which outlines the operating procedures for Software Version Management (SVM).
3. Important Warning: During the software update, it is crucial that the key remains on the emergency reader coil. Failure to do so could disrupt the update process.
4. Post-Update Reset: After the software update is complete, a bus sleep cycle must be performed. This involves cycling the key off and letting the vehicle sit for a few minutes to ensure the module resets properly.
5. Addressing Post-Update DTCs: In some cases, a DTC "C115E54: Inertial sensors no basic setting" might be stored in the Airbag Control Unit, -J234- (address 0015) after the update. If this occurs, basic settings for the inertial sensors must be performed to make this fault passive. It is not necessary to perform test plans for faults in the Chassis Control with Air Suspension, -J774- (address 0074). Once these steps are completed, any remaining faults can be cleared.

Required Tools or Parts

The repair primarily involves a software update. The new software part numbers and versions are:

• For A4, A5, Q7, Q8 models: New Software Part Number 8W1.907.064.EA, New Software Version 0630.
• For e-tron GT models: New Software Part Number 992.907.064.EA, New Software Version 0630.

Owner Action

If your 2023-2025 Audi vehicle experiences the "Ignition cannot be switched on" symptom or you suspect an underlying issue related to DTC U014100 or U043100, you should contact your authorized Audi dealership. The software update described in Technical Service Bulletin 2075236/1 is typically performed under warranty if your vehicle is still within the applicable warranty period. The service number for this operation is 5789, with a damage code of 0039. Labor operations include software updates (0151 0010, 0151 0060), self-diagnosis (0129 0050), and checking the vehicle for bus sleep mode (0689 0199).

Source: NHTSA ID 11009369