2025-2026 Audi A5/Q5/S5/SQ5 Engine Warning Lamp P157000 TSB

Audi has issued Technical Service Bulletin (TSB) 2080076/2 to address a specific issue affecting certain 2025-2026 Audi A5, Q5, S5, and SQ5 models. This bulletin details a condition where the engine warning lamp illuminates, and the diagnostic trouble code (DTC) P157000, indicating "Engine Control Module (ECM) locked," is stored in the Engine Control Module (ECM).

This TSB, identified as 2080076/2, provides a solution for this particular Audi A5 P157000 ECM locked problem. It outlines the diagnostic criteria and the necessary repair procedure, which primarily involves a software update to the vehicle's onboard systems.

Symptoms

Owners of affected 2025-2026 Audi A5, Q5, S5, and SQ5 vehicles may observe various symptoms depending on the engine type. For vehicles equipped with a 2.0-liter gasoline engine, the primary symptom is the engine failing to start on the first attempt. Additionally, several driver messages may appear in the instrument cluster, alerting the driver to a potential issue. Typically, after switching the ignition off and then back on, the engine will start normally, and no further issues will be experienced during that drive cycle.

For all other engine types, the symptoms are slightly different. Upon starting the vehicle, several driver messages will appear in the instrument cluster. In these cases, the vehicle might only be operable electrically, meaning the combustion engine will not start. Similar to the 2.0-liter gasoline engine, cycling the ignition off and on usually resolves the immediate issue, allowing the engine to start and operate without further problems.

Fault Codes / DTCs

The core of this issue is the logging of a specific diagnostic trouble code in the vehicle's Engine Electronics -J623- module (address word: 0001). The DTC that triggers this TSB is:

• P157000: "Engine Control Module (ECM) locked."

This Technical Service Bulletin 2080076/2 specifically applies if DTC P157000 is logged in the Engine Control Module (diagnostic address 0001). It is crucial to note that this TSB does not apply if the DTC "Transmission control module locked" is also logged in the transmission control module (diagnostic address 0002). The presence of the Audi A5 P157000 ECM locked code is the key indicator for this particular service action.

Diagnosis / Trigger Conditions

The underlying cause of the P157000 "Engine Control Module (ECM) locked" fault is identified as a software issue within the onboard supply control unit J519 (diagnostic address 0009). This software anomaly can lead to the ECM locking, preventing normal engine operation or starting on the first attempt.

Interestingly, workshop findings indicate that the customer complaint, particularly the engine not starting on the first attempt, cannot usually be reproduced by technicians during diagnostic checks. This suggests the issue might be intermittent or occur under specific, hard-to-replicate conditions. Despite the difficulty in reproducing the symptom, the logged P157000 DTC provides clear evidence of the problem.

Repair Procedure Summary

The resolution for the Audi A5 P157000 ECM locked condition involves performing a software update. This update is detailed in Audi's internal documentation as 2079690, specifically referred to as "00 Combined software update 03.10.00/C (28.13.01) KD2." This software package is designed to correct the fault within the onboard supply control unit J519 that causes the ECM to lock.

The repair process, as outlined in TSB 2080076/2, includes several labor operations to ensure a successful update:

• Software update, including connecting battery charger (Labor Operation 0151 0010): This initial step involves connecting a battery charger to the vehicle to maintain stable voltage during the software flashing process, which is critical to prevent interruptions or damage. The actual software update is then performed.
• Fixed rate for software update, including all required preliminary and follow-up work (Labor Operation 0151 0040): This covers the comprehensive process of preparing the vehicle for the update, performing the update itself, and subsequent tasks. These tasks include allowing the vehicle to enter a bus sleep cycle, conducting calibration drives, and any additional work necessary to ensure the new software is fully integrated and functioning correctly.
• Additional attempts after flash abort occurred (Labor Operation 0150 9999): In some cases, a software flash might abort. This labor operation accounts for the time and effort required for additional attempts to complete the update, with a specific allowance for each documented abort.

Important Warnings

Owners should be aware of the warranty implications for this service. Audi states: "If the vehicle is outside of any warranty, this Technical Service Bulletin is informational only." This means that while the TSB provides a repair solution, the cost of the repair may not be covered if the vehicle's warranty has expired. It is always advisable to check your vehicle's warranty status with an authorized Audi dealer.

Owner Action

If your 2025-2026 Audi A5, Q5, S5, or SQ5 is exhibiting an engine warning lamp with the P157000 "Engine Control Module (ECM) locked" DTC, or if you are experiencing the described starting and instrument cluster message symptoms, you should contact an authorized Audi dealership. The dealership technicians are equipped to diagnose the issue using the guidelines provided in TSB 2080076/2 and perform the necessary software update. This software update is the prescribed fix for the Audi A5 P157000 ECM locked condition.

Since this is a software-related issue and the vehicle is relatively new (2025-2026 model years), the repair is likely to be covered under the manufacturer's warranty. However, it is always best to confirm your warranty coverage with the dealership when scheduling your service appointment.

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Source: NHTSA ID: 11027424