2021-2023 Audi MIL On: EVAP System DTCs P148D00, P044200

Symptoms

Owners of affected Audi vehicles may notice that the Malfunction Indicator Lamp (MIL) illuminates on the dashboard. This "MIL is on" condition is often accompanied by specific diagnostic trouble codes (DTCs) related to the evaporative emission system.

Fault Codes / DTCs

When diagnosing the "Audi Q8 MIL on" issue, service technicians may find the following DTCs stored in the Engine Control Module (ECM J623, address word 0001):

Code	Description
P148D00	Evaporative Emission System Leak Detection Pump implausible frequency
P044200	EVAP Emission Control System (Small Leak) Leak Detected

No other relevant DTC entries should be logged in conjunction with these codes for this specific issue.

Technical Background

Audi has identified that the presence of DTC P148D00 or P044200, leading to the "MIL is on" light, is due to a software issue within the Engine Control Module (ECM J623). For specific configuration reasons, the ECM may store the P044200 code, indicating a "Small leak detected," even when there are no actual leaks present in the fuel tank system. This means the fault is often a false positive caused by the software.

Repair Procedure Summary

To address the "Audi Q8 MIL on" condition and clear the associated DTCs, the primary repair involves updating the software of the Engine Control Module (ECM J623). Technicians should follow the instructions outlined in Technical Service Bulletin 2073032/1, which directs them to:

1. Refer to and follow all instructions in TSB 2011732, which covers Software Version Management (SVM) operating procedures.
2. Update the ECM J623 (address word 0001) using the SVM action code 01A255 as specified in the software update details.
3. After the software update, it is crucial to ensure that there are no actual leaks in the fuel system. This step helps confirm that the software update has resolved the false detection and that no underlying physical issue remains.

Software Update Details

This repair involves updating the ECM J623 software to a newer version. The following table details the old and new software part numbers and versions for specific models:

Model	Diagnostic Address	Old Software Part Number	Old Software Version	New Software Part Number	New Software Version	SVM Code Input
Q7	0001	4M0907559D	<0003	4M0907559D	0004	01A255
Q7	0001	4M0907559L	<0002	4M0907559L	0003
Q8	0001	4M8907557F	<0001	4M8907557F	0002
Q8	0001	4M8907559M	<0002	4M8907559M	0003

Warranty Information

This software update is covered under Audi's warranty program. The claim types applicable are 110 for vehicles up to 48 months or 50,000 miles, and G10 for Audi Certified Pre-Owned (CPO) vehicles. If your vehicle falls outside of these warranty parameters, this Technical Service Bulletin is for informational purposes only, meaning the repair may not be covered free of charge.

• Service Number: 2048
• Damage Code: 0040
• Labor Operations: Software Update (Includes checking for DTCs) - 0151 0060 (Maximum 80 Time Units)
• Diagnostic Time: GFF (No allowance), Charge battery (2706 8950, 10 Time Units), Road test prior and after service (No allowance).
• Claim Comment: As per TSB 2073032/1.

Important Notes for Service Technicians

When flashing a control module via ODIS in supported vehicles, it is essential to always use DoIP (Diagnostic over Internet Protocol). To activate DoIP, technicians must select Administration>>General>>GFF Process>>DoIP communication>>Only allow DoIP communication. This setting will automatically reset at the end of the diagnostic session. DoIP is active when a red LED is observed on the VAS 6154(A) diagnostic tool.

All part and service references in this TSB 2073032/1 are subject to change. Technicians should always check with their Parts Department and/or ETKA for the latest information.

NHTSA ID: 10251622