Audi S5 Turbo Problems: Whistling & Power Loss Alert

I had an almost identical issue with my 2017 Audi A5 diesel. With some experience working on turbocharged engines, these symptoms immediately pointed to turbo actuator problems. The whistling sound combined with power loss and increased fuel consumption matches what I experienced. My car also showed inconsistent boost pressure sensor readings on the diagnostic tool. In my case, the electrical bypass valve was defective, causing irregular turbo wastegate operation. The repair involved: 1. Full diagnostic scan 2. Pressure testing of the turbo system 3. Replacement of the faulty actuator component 4. Recalibration of the turbo control system Total cost was 250 Euro including parts and labor. The repair resolved all symptoms, power returned to normal, fuel consumption improved, and the whistling disappeared. To help diagnose your specific case, could you share: Current mileage, Any recent maintenance history, Exact error codes from your diagnostic tool, Whether symptoms occur more during cold or hot engine conditions The turbo actuator system can be complex, and proper diagnosis is crucial before replacing parts. Your symptoms strongly suggest a boost pressure control issue, but confirming with detailed vehicle information would help narrow down the exact cause.

Thanks for the detailed response. My Audi S5 has 54208 KM on the clock and the last service was done just 2000 KM ago. After reading your experience, I ran another diagnostic test and confirmed a boost leak near the actuator connection. The error codes point specifically to a pressure sensor malfunction, with readings fluctuating between 0.2 and 1.8 bar under load. Interestingly, the symptoms are most noticeable when the engine is fully warmed up, especially during highway driving. The turbo wastegate seems to be struggling to maintain consistent pressure. I will get the turbo system pressure tested first before replacing any components. The cost estimate you provided seems reasonable. Did you need any special programming after the repair?

Thanks for the additional details about your S5. Looking at your error codes and symptoms, this definitely mirrors my experience even more closely than I initially thought. The fluctuating boost pressure readings between 0.2 and 1.8 bar are very similar to what my A5 showed before the repair. The fact that symptoms worsen when warm actually helps confirm the actuator fault diagnosis. The turbo system typically struggles more with pressure regulation at higher temperatures when the actuator valve is failing. After my repair, the workshop did need to perform a basic actuator calibration using their diagnostic system. This was included in the cost I mentioned earlier. The calibration is crucial, without it, the new actuator wont respond correctly to the engine management system. The recent service on your car suggests the issue is likely isolated to the turbo actuator rather than a maintenance-related problem. With those pressure readings, Id recommend getting the work done soon to prevent potential damage to other turbo system components. One additional tip from my experience: have them check the vacuum lines while testing the system. A minor vacuum leak can sometimes create similar symptoms, though your pressure readings strongly point to the actuator being the primary issue.

Current mileage is 54208 KM with the last service completed 2000 KM ago. Following your advice, I ran another diagnostic scan that revealed a boost leak near the actuator along with a pressure sensor malfunction. The readings are unstable, showing between 0.2 and 1.8 bar under load. The symptoms definitely get worse once the engine reaches operating temperature, particularly during highway driving. The turbocharger wastegate seems unable to maintain proper boost control. Based on your experience, I will arrange for pressure testing of the turbo system before replacing any parts. Your repair cost of 250 Euro sounds reasonable. I have scheduled an appointment with a workshop that specializes in turbo systems. They mentioned the repair would likely include recalibration of the boost control system after fixing the actuator fault. The timing seems right to address this now, before any potential damage occurs to other components. I appreciate the tip about checking vacuum lines during testing, will make sure they include that in the inspection. Would you mind sharing if any special programming was needed after your repair was completed?