2021-2022 Audi Q5 P029900 Turbo/Super Charger Underboost

Audi Technical Service Bulletin 01 22 21 2067162/1 addresses a common drive system fault affecting various 2021-2022 Audi Q5 and SQ5 models. Owners may experience a "Drive system: fault" message on the instrument cluster, accompanied by the Malfunction Indicator Lamp (MIL) illuminating. This condition is frequently linked to a lack of power, where the vehicle cannot achieve full boost, and is often identified by the Diagnostic Trouble Code (DTC) P029900.

This bulletin provides crucial information for diagnosing and resolving the Audi Q5 P029900 underboost issue, which can be caused by material accumulation within the charge air pipe. The affected models include the Q5 e quattro (2020-2022), SQ5 (2020-2022), Q5 and Q5 Sportback (2021-2022), and SQ5 Sportback (2021-2022), equipped with DLGA, CWGD, or DPVA engines.

Symptoms of the Audi Q5 P029900 Underboost

Owners of affected Audi vehicles may observe several key symptoms indicating a problem with the drive system:

• The Malfunction Indicator Lamp (MIL) is illuminated.
• The message "Drive system: fault" is displayed in the vehicle's instrument cluster.
• The vehicle experiences a noticeable lack of power, indicating that full boost cannot be achieved.

These symptoms are often reproducible during workshop findings, confirming the presence of an underlying issue.

Fault Codes (DTCs)

The primary diagnostic trouble code associated with this issue is:

• P029900: This code indicates "Turbo/Super Charger Underboost" and is typically stored in the Engine Control Module, specifically J623 (address word 0001).

Diagnosis and Trigger Conditions

To accurately diagnose the Audi Q5 P029900 underboost condition, technicians should perform the following steps:

• Check the specified and actual boost pressure values via the 0001 Measuring Value Block (MVB) in the diagnostic system.
• If there is a discrepancy between the specified and actual boost pressures, further checks for other charge air system leaks should be conducted.
• If no other charge air system leaks are present, the root cause is likely material accumulation inside the post intercooler charge air pipe. This specific issue has been observed in vehicles produced before October 14th, 2021. Figure 1 in the original bulletin illustrates this material accumulation.

Repair Procedure Summary

The recommended repair procedure to address the Audi Q5 P029900 underboost involves the replacement of the affected charge air pipe. The general steps are as follows:

• Verify the boost pressure discrepancy and rule out any other potential leaks in the charge air system.
• If the issue is confirmed to be the charge air pipe, proceed with its replacement.
• The labor operations for this repair include removing and reinstalling the pressure pipe, identified by service numbers 2141 1915 or 2141 1943.
• Diagnostic time for checking and clearing fault codes (0150 0000) is considered part of the existing labor operations, with a maximum of 50 Time Units (TU) allocated for diagnostics.

Required Tools and Parts

To perform this repair, specific parts and diagnostic tools are necessary:

• Pressure pipe: Part number 80A.145.673.* (The asterisk indicates potential variations; technicians should confirm the exact part number with their Parts Department or ETKA).
• Fasteners, Bolts, Nuts, and Screws: These should be obtained as needed, following the specifications in the ETKA/ELSA Repair Manual.
• Diagnostic Tool: A VAS tester, specifically VAS 6160/VAS 6150, running the current version of ODIS (Windows 10) software, is required for diagnosis and fault code management.

Warranty Information

Warranty coverage for this repair is provided under specific conditions:

• For vehicles within the standard warranty period, Claim Type 110 applies, covering up to 48 Months or 50,000 Miles.
• For Certified Pre-Owned (CPO) vehicles, Claim Type G10 is applicable, requiring verification of owner eligibility.
• If the vehicle falls outside of any active warranty, this Technical Service Bulletin 01 22 21 2067162/1 serves purely as informational guidance. All warranty claims must adhere to the guidelines outlined in the Audi Warranty Policies and Procedures Manual.

Owner Action

If your 2021-2022 Audi Q5 or SQ5 exhibits a "Drive system: fault" message, MIL illumination, or a noticeable lack of power, especially if accompanied by the Audi Q5 P029900 underboost code, it is recommended to have your vehicle inspected by an authorized Audi service center. Providing them with this TSB number (01 22 21 2067162/1) can assist in a quicker and more accurate diagnosis and repair.

---

Source: NHTSA ID: 10212932