2021-2025 Audi MIL On, Rough Engine Due to Loose Oil Cap TSB

Owners of various 2021-2025 Audi models equipped with the 2.0 ltr TFSI engine may encounter issues such as an illuminated Malfunction Indicator Lamp (MIL), rough engine operation, and visible oil leaks. Audi Technical Service Bulletin (TSB) 2070915/2, released on March 10, 2026, addresses these concerns, frequently linking them to a simple yet critical problem: an incorrectly installed engine oil filler cap. This bulletin provides guidance for technicians to diagnose and resolve the issue.

This TSB, identified as 2070915/2, is a revision of a previous bulletin, with the current version adding details on workshop findings and warranty information. The primary focus is to ensure the Audi loose oil filler cap is properly seated, which can prevent a range of performance and warning light issues.

Symptoms Owners May Notice

If your 2021-2025 Audi is affected, you might observe one or more of the following symptoms:

• "MIL on.": The Malfunction Indicator Lamp, commonly known as the check engine light, illuminates on your dashboard. This indicates that the engine control unit has detected a fault.
• "The engine is running rough.": You may experience noticeable vibrations, misfires, or a general lack of smoothness from the engine, particularly during idle or acceleration.
• "There is oil on the engine near the oil filler cap.": A visual inspection might reveal oil residue or seepage around the engine oil filler cap, indicating a poor seal.

Associated Fault Codes (DTCs)

While the engine control unit's event memory may not always contain an entry, the following Diagnostic Trouble Codes (DTCs) are commonly associated with an incorrectly installed Audi loose oil filler cap:

These DTCs point to issues that can arise from an unsealed or improperly sealed intake system, which a loose oil filler cap can contribute to by allowing unmetered air into the engine.

Diagnosis and Trigger Conditions

The technical background of TSB 2070915/2 indicates that the root cause of these symptoms and DTCs is often an incorrectly installed engine oil filler cap. Even though the fault codes might suggest complex system failures, the initial diagnostic step should involve checking the oil filler cap's seating. A visual inspection, as illustrated in the bulletin's figures, can quickly identify if the cap is not fully closed or is misaligned.

Repair Procedure Summary

The repair for an Audi loose oil filler cap is straightforward and focuses on ensuring a proper seal. The steps outlined in TSB 2070915/2 involve:

1. Inspection: Verify that the oil filler cap is indeed not closed correctly or is improperly seated. This might be evident from the visual cues like oil seepage.
2. Cleaning: Before attempting to re-install the cap, thoroughly clean the contact surfaces of both the oil filler cap and the filler neck on the engine. This removes any debris or oil residue that could prevent a proper seal.
3. Correct Installation: Insert the oil filler cap into the correct position, ensuring it is fully tightened and sealed. This simple action can resolve the MIL illumination, rough running, and oil leak issues.

The TSB also lists labor operations such as