RS6 Engine Issues: Rich Fuel Mix Causing Power Loss

Having some experience working on Audis, I ran into a very similar issue with my 2018 RS7. The symptoms you describe match exactly what I experienced, poor fuel economy, jerky acceleration, and that dreaded check engine light. After monitoring the air-fuel ratio, my mechanic diagnosed a faulty fuel injector that was causing a rich mixture. One of the intake manifold sensors also showed irregular readings. The repair involved replacing the problematic fuel injector and cleaning the remaining ones. The total repair came to 515 Euro, but it completely resolved the issues. The engine ran smoothly again and fuel consumption returned to normal levels. To help diagnose your specific case, could you share: Current mileage on your RS6, When was the last fuel system service performed, Are you using recommended fuel grade, Did the issue start suddenly or develop gradually, Any other warning lights besides check engine These details would help determine if your case might be similar to what I encountered with my RS7.

Thanks for checking. Just did my last major service at 25000 KM about 3 months ago. The fuel injectors were not part of that service scope. My 28602 KM definitely suggests its time for a thorough fuel system inspection. Your fix sounds promising given the similar symptoms. The air-fuel ratio issues started gradually over the past few weeks. Running strictly on high octane fuel as recommended, but the poor fuel economy and performance problems keep getting worse. From what you described, I should have the fuel injectors checked first before exploring other potential issues with the catalytic converter.

Good to hear back about your RS6. Based on your mileage and timeline, this definitely points toward fuel delivery issues similar to what I encountered. The gradual onset particularly matches my experience, as faulty fuel injectors tend to deteriorate progressively rather than fail suddenly. Since your air-fuel ratio problems started after the major service, its worth having the intake manifold checked as well. In my case, the rich fuel mixture was initially caused by a single problematic injector, but had started affecting the entire fuel system performance. Your consistent use of high octane fuel rules out fuel quality issues. The increasing fuel consumption and performance problems strongly suggest the fuel injectors need attention. A thorough fuel system cleaning might resolve the issue before requiring full injector replacement like I needed. My suggestion would be to have a diagnostic test focusing on: 1. Individual fuel injector performance 2. Overall air-fuel ratio readings 3. Intake manifold sensor values 4. Air filter condition This systematic approach helped identify the root cause in my RS7 without unnecessary parts replacement.

Thanks for the detailed suggestions. Just scheduled a diagnostic appointment for next week. Will focus on getting the fuel injectors and intake system thoroughly checked first, given how closely my symptoms match your experience. The oxygen sensor readings from my OBD scanner confirm the rich fuel mixture, which aligns with your fuel injector diagnosis. Really hoping a good cleaning might resolve it without needing full replacement of the injectors. But at least I now have a clear starting point for the diagnostic process, especially since the check engine light matches the fuel system symptoms youve described. Definitely feels better going in with some real-world insight rather than just guessing. Will update once I get the diagnostic results and know whether its the fuel injectors or if we need to look at other components like the catalytic converter or spark plugs.