2021 Audi MIL On: Cylinder Misfire DTCs P0300-P0306 TSB

Symptoms

Owners of affected Audi vehicles may notice the Malfunction Indicator Lamp (MIL) illuminating on the dashboard. This typically indicates a problem with the engine's emissions system. The underlying cause for this TSB is a 2021 Audi Q8 cylinder misfire condition.

Fault Codes / DTCs

When diagnosing the illuminated MIL, technicians may find one or more of the following Diagnostic Trouble Codes (DTCs) stored in the vehicle's system:

Code	Description
P0300	Random/Multiple Cylinder Misfire Detected
P0301	Cyl.1 Misfire Detected
P0302	Cyl.2 Misfire Detected
P0303	Cyl.3 Misfire Detected
P0304	Cyl.4 Misfire Detected
P0305	Cyl.5 Misfire Detected
P0306	Cyl.6 Misfire Detected

Diagnosis and Trigger Conditions

The primary trigger for this issue is an unoptimized software calibration within the Engine Control Module (ECM), specifically the J623 control unit (address word 0001). This software can lead to cylinder misfires, which in turn cause the MIL to illuminate and the aforementioned DTCs to be stored. The recommended fix for the 2021 Audi Q8 cylinder misfire is a software update.

Repair Procedure Summary

Technical Service Bulletin 01 23 91 2069038/5 outlines a software update procedure to resolve the cylinder misfire condition. This TSB, dated November 1, 2023, supersedes previous bulletin Group 01 number 23-80 from October 2, 2023, and also replaces earlier Pending Service Solutions (PSS) TSBs 2054182 and 2058038. The repair involves:

1. Following the instructions detailed in TSB 2011732, which covers Software Version Management (SVM) operating procedures.
2. Updating the Engine Control Module (ECM), identified as J623 (address word 0001), using the appropriate SVM action code. For example, specific MY 20 Q7 vehicles use SVM code 01A255. The update will bring the ECM software to a newer version, such as 4K0907559A version 0008 for MY 19 A6/A7 or 4M8907559A version 0004 for MY 19-20 Q8.

This optimized software is designed to correct the misfire issue and prevent the MIL from illuminating.

Required Tools or Parts

To perform the software update, technicians will need a specialized diagnostic tool:

• VAS 6160/VAS 6150: A VAS tester equipped with the current version of ODIS (Windows 10) software.

Important Warnings

Audi specifies that if your vehicle is outside of its warranty period, this Technical Service Bulletin is for informational purposes only. Warranty claims are covered for up to 48 months or 50,000 miles. For Audi Certified Pre-Owned (CPO) vehicles, the G10 claim type applies, and ownership must be verified.

Owner Action

If your 2021 Audi A6, A7, Q7, Q8, or A6 allroad is displaying an illuminated MIL and you suspect a 2021 Audi Q8 cylinder misfire, it is recommended to schedule an appointment with an authorized Audi dealership. They will be able to diagnose the vehicle, confirm the presence of the relevant DTCs, and perform the necessary software update to the Engine Control Module (ECM) as per TSB 01 23 91 2069038/5.

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Source: NHTSA ID: 10245524