2025 Audi A5, S5, Q5, SQ5 MIL On with DTC P050600

Audi has issued Technical Service Bulletin (TSB) 2079911/3 to address a specific issue affecting certain 2025 Audi A5, S5, Q5, and SQ5 models equipped with the V6 TFSI engine. This bulletin details a condition where the Malfunction Indicator Lamp (MIL), also known as the 'Check Engine' light, illuminates, and a diagnostic trouble code (DTC) P050600 is stored in the vehicle's Engine Control Module (ECM).

This TSB, identified as 2079911/3, supersedes the previous Pending Service Solution TSB 2078915. It outlines a software-related problem that can lead to noticeable symptoms, primarily concerning the engine's idle speed. Owners experiencing the Audi P050600 MIL should be aware of this official guidance from Audi.

Symptoms

Owners of affected 2025 Audi A5, S5, Q5, or SQ5 vehicles may observe the following symptoms:

• Malfunction Indicator Lamp (MIL) or Exhaust Emissions Warning Light: This warning light will be displayed in the instrument cluster shortly after starting the engine. This is often the first and most noticeable sign of the underlying issue.
• Noticeably Low Engine Speed: In some isolated cases, the engine speed may be unusually low, particularly during idle. This can manifest as rough idling or the engine feeling like it's struggling to maintain a steady RPM.

It's important to note that sometimes there may be no direct customer complaint related to these symptoms. Instead, the DTC P050600 might be discovered by a technician during diagnostic checks for an unrelated concern.

Fault Codes / DTCs

When diagnosing this issue, technicians will find specific diagnostic trouble codes (DTCs) and symptom codes logged in the Engine Control Module (ECM) -J623- (address word 0001). The primary code associated with this problem is:

Code	Description	Module
P050600	Idle Speed Control, RPM below spec value	Engine Control Module -J623-
4008	Symptom code (static/intermittent)	Engine Control Module -J623-

This DTC P050600, combined with symptom code 4008, indicates that the engine's idle speed is not within its specified range, pointing directly to a control issue within the ECM.

Technical Background

The root cause of the Audi P050600 MIL and associated idle speed issues is identified as a software problem. This software anomaly resides within two key control units:

• Engine Control Unit (ECU): Specifically, the software in the engine control unit, which has a diagnostic address of 0001, is affected. The ECU is responsible for managing various engine functions, including fuel injection, ignition timing, and idle speed.
• Main Control Unit for Drive System and Running Gear Systems (HCP1): The software in this unit, with a diagnostic address of 812C, also contributes to the problem. HCP1 is a broader control module that integrates functions related to the vehicle's powertrain and chassis systems.

This dual software issue leads to incorrect idle speed control, triggering the P050600 DTC and the illumination of the MIL.

Repair Procedure Summary

The resolution for the Audi P050600 MIL and the underlying software issue is a comprehensive software update. This procedure is detailed in a separate bulletin, TSB 2079690, titled "00 Combined software update 03.10.00/C (28.13.01) KD2."

Technicians will perform the following general steps:

1. Connect Battery Charger: A stable power supply is crucial during software updates to prevent interruptions that could damage control modules. A battery charger must be connected to maintain adequate voltage throughout the process.
2. Perform Software Update: The primary step involves flashing the updated software version (03.10.00/C (28.13.01) KD2) to the affected control units (ECU and HCP1). This update corrects the faulty programming that causes the idle speed control issue.
3. Preliminary and Follow-up Work: This includes necessary steps like ensuring the vehicle enters a bus sleep cycle and performing calibration drives. Calibration drives help the newly updated software adapt to the vehicle's specific operating conditions and ensure all systems are functioning correctly.

Required Software / Part Numbers

The specific software update required to resolve this issue is identified as 03.10.00/C (28.13.01) KD2. This software package is applied to the vehicle's control units. While no specific hardware parts are listed for replacement, a battery charger is a required tool for the update process.

Warranty Information

Audi has provided specific guidelines for warranty claims related to TSB 2079911/3:

• Claim Type: If the vehicle is outside of its warranty period, this Technical Service Bulletin is considered informational only. This means the repair may not be covered free of charge if the warranty has expired.
• Service Number: 2470
• Damage Code: KD2
• Labor Operations:
  • 0151 0010: Software update, including connecting a battery charger. This operation is associated with specific labor times (SRT).
  • 0151 0040: Fixed rate for the software update, covering all required preliminary and follow-up work, including bus sleep cycle, calibration drives, and any additional work. This operation is allocated 130 Technical Units (TU).
  • 0150 9999: In cases where a flash abort occurs and additional attempts are needed, an additional lump sum of 50 TU can be claimed per documented attempt.
• Claim Comment: As per TSB 2079911/3.

All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty. Importantly, when performing the combined software update, time stamps are not required for billing under warranty, and the update can even be performed by non-productive personnel.

Important Warnings

Owners and technicians should be aware of the following important points:

• The complaint, such as the Audi P050600 MIL, does not typically occur during normal vehicle operation. It is more likely to manifest under specific conditions.
• A low charge level in the vehicle's battery can occur during extended stationary periods, such as during transportation or when the vehicle is at the workshop. This condition might contribute to the manifestation of the software issue.
• All parts and service references within TSB 2079911/3 are subject to change. Always consult with your Audi Parts Department and/or ETKA for the most current information and part bulletins.

Owner Action

If you own a 2025 Audi A5, S5, Q5, or SQ5 and are experiencing the MIL illuminating with potential idle speed issues, or if you suspect your vehicle might be affected by the Audi P050600 MIL, it is recommended to contact your authorized Audi dealership. The software update described in TSB 2079911/3 is the prescribed fix. Under warranty, this repair should be performed free of charge. Your dealership can confirm if your specific vehicle is covered by this Technical Service Bulletin and schedule the necessary software update.

NHTSA ID: 11027413