SQ5 TDI Boost Control Failure Causing Multiple Issues

Having worked on similar issues with my 2020 S4 TDI, I can share some relevant experience. The symptoms you describe closely match what I encountered, particularly the turbo lag and whistling sound during acceleration. After multiple diagnostic tests, my workshop identified a defective wastegate valve causing irregular boost pressure control. The check engine light was triggered by inconsistent readings from the MAP sensor due to the unstable boost pressure. The repair involved: Complete diagnosis of the turbocharger system, Replacement of the wastegate valve, Recalibration of the boost pressure control, System testing under load Total cost came to 860 Euro including parts and labor. The repair resolved all issues, power delivery returned to normal, fuel consumption improved, and the whistling noise disappeared. To provide more specific advice for your case, could you share: Current mileage, When the symptoms first appeared, Any recent maintenance or modifications, Specific error codes from the check engine light, Whether symptoms get worse under certain conditions This information would help determine if your issue is similar and if the same repair approach might work for your vehicle.

Last service at 127138 KM showed normal readings but the turbocharger issues started shortly after. After running diagnostics, the check engine warning pointed to a failing boost pressure sensor. The mechanic also found a vacuum leak that was affecting the turbo performance. The combination of these issues matches exactly what you experienced with the irregular boost pressure control. Got it fixed with: New boost pressure sensor, Vacuum line replacement, System pressure test, Full turbocharger inspection Total repair cost was 690 Euro and the turbo lag is completely gone now. The engine runs smooth again with normal fuel consumption. Worth checking these components if anyone else encounters similar symptoms.

Thanks for the update on your SQ5 repair. Your findings really resonate with my S4 TDI experience. The vacuum leak combined with faulty boost pressure sensor explains the symptoms perfectly. In fact, after my initial wastegate repair, I also had to address similar vacuum line issues six months later. The intercooler system can be quite sensitive to even small vacuum leaks, which often lead to inconsistent boost pressure and that characteristic whistling noise. Good call on getting the full system pressure test done, its critical for spotting these issues before they cause more extensive turbocharger damage. Your repair cost at 690 Euro was actually better than my 860 Euro bill, likely because you caught it earlier. The improved fuel consumption alone will help offset that cost over time. For future reference, regular inspection of vacuum lines and boost pressure components can help catch these problems early. The throttle body response tends to be one of the first indicators when the turbocharger system starts developing issues.

I appreciate the detailed feedback on similar turbocharger system problems. The early detection through vacuum line inspection definitely saved me money compared to your repair. This matches what the mechanic mentioned about catching boost-related issues before they escalate. The pressure sensor replacement and vacuum fixes completely transformed the cars performance. No more check engine light, turbo lag is gone, and fuel economy is back to normal. Really glad I sought advice here before going to the shop, helped me communicate the issues more effectively to the mechanic. The intercooler and throttle body are running perfectly now with the new parts. For anyone reading this in the future: if you notice similar boost pressure problems, dont wait. Getting it checked early likely prevented more expensive turbocharger repairs in my case. A 690 Euro repair bill was worth it considering the alternative of major turbo system damage. The car runs like new again, quick throttle response, smooth idle, and proper boost pressure at all speeds.

Hello, I intend to buy a 2019 SQ5 TDI (100,000 km) but Audi explained to me that the engine has serious failures: oil leak, injector breakage and EGR fouling for example... This is not very encouraging! Can you tell me more? Does anyone own a vehicle of this type? Thank you for your answer, best regards.

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It's important to approach this purchase with caution given the issues you've mentioned. An oil leak can lead to engine damage if not addressed promptly, and injector breakage can cause poor engine performance and increased emissions. EGR fouling can also affect engine efficiency and emissions. I recommend having a thorough pre-purchase inspection done by a qualified mechanic to assess the extent of these issues and estimate repair costs. This will help you make an informed decision. If you have any further questions or need more guidance, feel free to ask.