Audi A7 Idle Issues Point to Fuel System Problems

Had a similar issue on my 2016 Audi A6 3.0T last year. I have some experience working on cars but mainly routine maintenance. The symptoms you describe match exactly what happened after I changed my fuel filter. The check engine light came on and the engine developed a rough idle. The reduced power and stalling issues were particularly noticeable at stops. The problem turned out to be an incorrectly entered fuel rail pressure value in the engine management system after the filter change. The workshop recalibrated the fuel system settings and cleared the error codes. Total cost was 45 Euro for diagnostics and reprogramming. Before suggesting more specific solutions, could you share: Have you had any recent fuel system work done? What error codes is the check engine light showing? Does the rough idle get worse with engine temperature? Are you experiencing any unusual fuel efficiency changes? This could help determine if your issue is similar and if a simple recalibration might solve it, or if there might be a different underlying problem with the fuel pump or other components.

Last service done at 138000km. The error codes from my OBD reader show P0193 and P0087, suggesting a fuel rail pressure sensor issue. The rough idle definitely gets worse as the engine warms up, and fuel efficiency has dropped by about 15%. Haven't had any recent work done on the fuel system. I also noticed the pressure readings are fluctuating wildly on my diagnostics tool, showing a pressure drop from normal operating levels. This seems to confirm potential issues with either the pressure sensor or fuel rail components. Would it be worth trying to clean the system first, or should I go straight for sensor replacement?

Thanks for the additional details. Those specific error codes on your A7 match what my A6 showed initially, but my case turned out to be more complex than just the recalibration I mentioned before. My fuel rail pressure sensor was indeed faulty, causing similar symptoms to yours, engine misfire, rough idle that worsened with heat, and inconsistent pressure readings. I first tried cleaning the system with fuel injector cleaner, but it didn't resolve the check engine light or performance issues. The fluctuating pressure readings are a strong indicator of a failing sensor or regulator. In my case, the mechanic found that both the pressure sensor and fuel pressure regulator were degraded. The total repair involved: Replacing fuel rail pressure sensor, Installing new fuel pressure regulator, Full system diagnostic scan, Clearing fault codes Final cost was around 650 Euro including parts and labor. The repair completely resolved the rough idle and restored normal power. Fuel consumption returned to normal within two tank fills. Given your similar symptoms and error codes, I would skip the cleaning attempt and go straight for proper diagnosis and likely sensor replacement. The wild pressure fluctuations you are seeing typically indicate hardware failure rather than just contamination in the fuel system.

Thanks for the detailed feedback about your A6 repair experience. The matching error codes and symptoms definitely point to a similar issue in my A7. Since the pressure readings are so erratic and the engine misfire gets worse with temperature, I agree that trying to clean the system would likely be a waste of time and money. I will book the car in for diagnosis and likely need the fuel rail pressure sensor and regulator replaced. The 650 Euro cost estimate helps set my expectations. Better to fix it properly now than risk further fuel system damage or complete engine failure from running with incorrect pressure. Will update once the repairs are done in case anyone else encounters similar fuel pressure problems with their 3.0T engine. These symptoms and error codes seem to be a common pattern pointing to sensor and regulator failure around this mileage.