RS3 Turbo Issues: Whistling & Power Loss Symptoms

As someone with some repair experience, I encountered a very similar issue with my 2019 RS4. The symptoms you describe match exactly what I experienced, especially that characteristic whistling and hissing during acceleration, combined with the engine sensor warnings. The charge sensor malfunction initially confused my workshop, but they discovered loose wiring connections affecting both the airflow sensor and temperature readings. The root cause was a deteriorated wiring harness connector near the air intake system. These connections can become loose due to engine vibration and heat cycles. The fix involved replacing the damaged connector and properly securing the wiring harness. Total repair cost was 95 Euro, mostly covering labor since the replacement parts were minimal. Before suggesting specific fixes, could you provide: Current mileage, When the symptoms first appeared, Whether the temperature fluctuation warnings are constant or intermittent, If the engine performance issues get worse when the engine is hot This information would help confirm if your issue matches what I experienced. The combination of reduced power and sensor malfunctions often points to air intake measurement problems, but its best to verify all symptoms match before making assumptions.

Thanks for your reply and helpful suggestions! Just to share the details: my odometer shows 117101 KM, and the last service was performed on schedule. The symptoms started appearing intermittently about a week ago, but are now constant. The temperature sensor readings fluctuate wildly, especially when the engine is warm. The engine performance drops noticeably after about 15 minutes of driving. The air temperature readings are most erratic during acceleration, which matches what you mentioned about the airflow sensor connections. Based on your experience, it does sound quite similar to my situation. Good to know the repair costs were reasonable in your case. I will have the air intake system and wiring connections checked first.

Your symptoms do exactly mirror what I experienced with my RS4. The timing of the issues, starting intermittently and becoming constant, plus the correlation with engine temperature matches the pattern I saw with the faulty wiring harness. In my case, the automotive sensor readings also showed those wild fluctuations during acceleration. The engine temperature sensor and charge sensor data were particularly unstable once the engine warmed up, just like youre describing. After fixing the wiring connector near the air intake system, all these issues disappeared completely. The whistling noise, power loss, and erratic temperature readings were all linked to that single connection point affecting multiple sensor readings. Since you mention similar mileage and operating conditions, Id strongly suggest having the workshop focus on inspecting the wiring harness connections first, particularly around the air sensor cluster. This could save diagnostic time and costs, as its a known weak point in these engines. Just monitor the engine temperature while driving to the workshop. If you notice the power dropping significantly after those 15 minutes, try to schedule the repair soon to prevent any potential secondary issues from developing.

Thanks everyone for the detailed responses. I feel much more confident now about the likely cause of my problems. The connection between the temperature sensor issues and the wiring harness makes perfect sense, especially since my symptoms match so closely with what others experienced. Will book an appointment with my workshop tomorrow and ask them to specifically check the air intake system wiring connections and sensor cluster. Having the repair cost reference of around 100 Euro is really helpful for budgeting. The fact that its likely just a wiring harness issue rather than a major engine sensor failure is a relief. Good call on monitoring the engine temperature during the drive to the workshop. Will try to book an early morning appointment to minimize running the engine when its having these issues. Just hoping the fix will be as straightforward as replacing the damaged connector and securing the wiring properly. Will update once its resolved.