2025 Audi A5/S5/Q5 MIL On with DTC P050600 TSB

Symptoms

Owners of affected 2025 Audi A5, S5, and Q5 models equipped with the V6 TFSI engine may notice the Malfunction Indicator Light (MIL), commonly known as the 'Check Engine' light, illuminating on the instrument cluster. This may also appear as an "exhaust emissions warning light is displayed" message. In some instances, the engine speed might be noticeably low after starting the vehicle. The presence of the "Audi A5 MIL on P050600" condition is a key indicator of this issue.

Fault Codes / DTCs

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

• DTC P050600: "Idle Speed Control, RPM below spec value, symptom code 4008 static/intermittent"

This DTC indicates that the engine's idle speed is lower than the specified value, and the symptom code 4008 further clarifies the nature of this idle speed control malfunction as either constantly present or occurring intermittently.

Diagnosis / Trigger Conditions

The root cause of the "Audi A5 MIL on P050600" and associated symptoms is identified as a software issue. This problem resides within two key control units: the engine control unit (diagnostic address 0001) and the main control unit for drive system and running gear systems (HCP1, diagnostics address 812C). The issue typically does not occur during normal vehicle operation. Instead, it is often linked to a low charge level that can develop during extended stationary periods, such as during vehicle transportation or while the vehicle is at a workshop.

Repair Procedure Summary

Audi Technical Service Bulletin (TSB) 2079911/2 outlines the necessary steps to resolve the software issue causing the MIL illumination and DTC P050600. This bulletin supersedes a previous document, Pending Service Solution TSB 2078915, which also addressed the "01 MIL on, DTC P050600 Stored in ECM - V6 TFSI" condition. The recommended repair involves performing a software update.

Technicians are instructed to check for the visibility of TSB 2079690, titled "00 Combined software update 03.10.00/C (28.13.01) KD2," for the specific vehicle. If this update is available, the software update described in TSB 2079690 must be performed. This update targets the software in the affected control units to correct the idle speed control issue.

Required Tools or Parts

The primary requirement for this repair is the appropriate software update package. During the software update process, a battery charger must be connected to the vehicle to maintain stable voltage.

Important Warnings for Owners

• Warranty Coverage: If your vehicle is outside of its warranty period, this Technical Service Bulletin (TSB 2079911/2) serves as informational guidance only. This means that the cost of the repair may not be covered by Audi. Owners should consult their dealership regarding warranty status and potential costs.
• Combined Software Update: If a combined software update, as described in TSB 2079690, has already been performed on your vehicle, this specific bulletin's instructions may not apply. Always confirm with your service center.
• Dealer Operations: For warranty claims related to the software update, time stamps are not required for billing. This allows technicians to work on other vehicles simultaneously, and the update can even be performed by non-productive personnel, streamlining the service process.

Owner Action

If your 2025 Audi A5, S5, or Q5 displays a "MIL on" light, an exhaust emissions warning, or experiences noticeably low engine speed, and you suspect the "Audi A5 MIL on P050600" issue, it is recommended to schedule an appointment with an authorized Audi service center. Provide them with the details of the symptoms you are experiencing. The dealership technicians will be able to diagnose the vehicle, confirm the presence of DTC P050600, and perform the necessary software update as per TSB 2079911/2 to resolve the issue.

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Source: NHTSA ID 11027337