2025 Audi A3 / S3 Engine Warning Lamp DTC P162400

Owners of certain 2025 Audi A3 and S3 vehicles may notice their engine warning lamp illuminating permanently after starting the engine. This condition is addressed by Technical Service Bulletin (TSB) 45 25 53 2076568/1 and is linked to a specific software issue within the vehicle's electromechanical brake servo control unit. While the warning lamp is active, the functionality of both the electromechanical brake servo and the engine control unit remains unimpaired.

Symptoms

The primary symptom reported by owners is a permanently illuminated engine warning lamp on the instrument cluster immediately after the engine is started. This indicates a detected fault, even though the vehicle's driving performance and braking capabilities are not affected. If you experience an Audi S3 engine warning lamp that stays on, this bulletin may apply to your vehicle.

Fault Codes / DTCs

When this condition occurs, specific Diagnostic Trouble Codes (DTCs) are logged in the vehicle's control units:

• P162400: This code is found in the engine control unit and is described as "Requirement malfunction lamp on active" with symptom number 17324. It signifies that the engine control unit is requesting the illumination of the malfunction indicator lamp.
• U034B00: This code is logged in the electromechanical brake servo control unit and is described as "Software Incompatibility with Brake Booster Control" with symptom number 500032. This points to the root cause of the issue: a software discrepancy.

Technicians have also noted that the software version in the electromechanical brake servo control unit is 0562 when this issue is present.

Technical Background

The root cause of the Audi S3 engine warning lamp and associated DTCs is identified as a software issue within the electromechanical brake servo control unit. This software anomaly can inadvertently trigger the engine warning light during the vehicle's start-up sequence.

Important Warnings for Owners

Audi has issued critical guidance for both owners and technicians regarding this issue, outlined in TSB 45 25 53 2076568/1. It is crucial to understand these points to avoid unnecessary repairs and costs:

• Do Not Replace Components: Audi explicitly states, "Do not replace any components for this condition since this will not resolve the customer's concern." Attempting to replace parts will not fix the underlying software issue.
• Warranty Implications: "Replacing parts or attempting repairs will not fix the problem. Unjustified work/replacement parts will be charged back. Invoicing under warranty is not permitted." This means owners could be charged for parts and labor if a dealer performs unauthorized repairs.
• No Immediate Repair Needed: While a permanent solution is under development, Audi advises that "no repairs are necessary at this point" beyond the temporary workaround. The vehicle's core functionality is not impaired.
• Solution Timeline: A permanent software solution is "expected to be available by the end of the first quarter of 2025," though this timeline is "subject to change." Owners should be aware that a definitive fix is coming but not yet released.

Temporary Workaround

For owners experiencing the permanently illuminated engine warning lamp, Audi provides a temporary workaround. Technicians can "Erase the DTC in the electromechanical brake servo and engine control unit and test drive the vehicle, ensuring to start the engine multiple times." This action will clear the warning light temporarily, but the underlying software issue means the DTCs may reappear until a permanent fix is implemented.

Manufacturer's Remedy and Future Solution

Audi is actively working on a permanent software solution for this condition. The production solution is currently "Under analysis," with an expected availability by the end of the first quarter of 2025. Until this solution is released, dealers are instructed to:

1. Inform customers that a permanent fix is anticipated by the end of Q1 2025, but this date is subject to change.
2. Advise against replacing any components, as this will not resolve the issue.
3. Create a Pending Service Solutions (PSS) record for the vehicle in the PSS application via AccessAudi. This ensures that the customer's concern is documented and tracked for when the permanent solution becomes available. The TSB 45 25 53 2076568/1 serves as the primary reference for this process.

NHTSA ID: 11013722