2025 Audi Q5/SQ5 Engine Warning Lamp TSB 2081184/1

Symptoms

Owners of affected 2025 Audi Q5 and SQ5 vehicles may notice one or both of the following conditions:

• "The engine warning lamp lights up."
• "The air conditioning is not working."

These symptoms indicate a potential issue within the vehicle's thermal management system, often accompanied by specific diagnostic trouble codes.

Fault Codes / DTCs

When diagnosing this issue, technicians may find one or more of the following diagnostic trouble codes (DTCs) logged in the thermal management control unit (00C5):

• U366500: "Local data bus 23 faulty"
• P2D8B00: "Fan 2 Control Module Performance"
• P2D8800: "Fan 1 Control Module Performance"

These codes point to a problem with the fan control modules or the data communication within the thermal management system.

Diagnosis / Trigger Conditions

The root cause for the Audi Q5 engine warning lamp U366500 and related DTCs is an incorrectly fitted earth connection. Specifically, the earth connection at earth point 642, which serves the electrically controlled fan, may not have been properly secured during manufacturing. This manufacturing defect affects vehicles produced within a specific period before May 28, 2025, when a production solution was implemented. The fault can be intermittent or static, meaning it may appear consistently or only under certain conditions.

Repair Procedure Summary

To resolve the Audi Q5 engine warning lamp U366500 issue and other related symptoms, Audi Technical Service Bulletin 2081184/1 outlines a specific repair procedure. The primary step involves checking and, if necessary, modifying the earth connection at earth point 642. This earth point is located on the front right side of the vehicle and is crucial for the proper operation of the electrically controlled fan.

The repair process typically begins with the removal and installation of the front wheel housing liner to gain access to earth point 642. Once accessible, the technician will inspect the connection for any damage or improper fitting. The necessary modification ensures a secure and reliable earth connection, restoring proper function to the electrically controlled fan and the thermal management system. The labor operations associated with this repair include 'Remove and install front wheel housing liner' (labor code 6616 1900) and 'Modify earth point' (labor code 9798 4999).

Important Warnings

Owners should be aware of the warranty conditions related to this Technical Service Bulletin 2081184/1. If your 2025 Audi Q5 or SQ5 vehicle is outside of its warranty period, this TSB is considered informational only, and any repair costs may not be covered by Audi. It is always recommended to consult with an authorized Audi service center to understand your specific warranty coverage.

Owner Action

If you are experiencing an "engine warning lamp lights up" message or "air conditioning is not working" in your 2025 Audi Q5 or SQ5, and especially if you suspect a thermal management system fault, it is recommended to visit an authorized Audi dealership. The technicians will perform a diagnostic scan to confirm the presence of DTCs such as U366500, P2D8800, or P2D8B00. They will then proceed with the repair outlined in TSB 2081184/1 to inspect and correct the earth connection at earth point 642. Ensure to mention the symptoms and any warning lights you have observed. While the TSB does not specify a cost, repairs performed under warranty should be free of charge.

Source: NHTSA ID 11031037