SQ5 Turbo Issues: Stalling, Whistling and Power Loss

Had similar symptoms on my 2016 A6 3.0 TDI. The boost pressure issues were caused by a faulty turbo actuator, which was causing inconsistent wastegate operation. Main symptoms matched yours: Power loss during acceleration, Whistling from engine bay, Increased fuel consumption, Rough idle and occasional stall The turbo system inspection revealed a failed electrical bypass valve and worn actuator valve. The entire actuator assembly needed replacement as the internal components were showing significant wear. This was a serious issue requiring immediate attention, as continued driving could have led to complete turbo failure. The repair involved: Full diagnostic check of the turbo system, Removal and replacement of turbo actuator, New actuator valve installation, Recalibration of boost pressure settings, Testing under various load conditions Post-repair performance returned to normal, with proper boost pressure readings and no more erratic behavior. Would strongly recommend getting this checked by a qualified turbo specialist, as incorrect diagnosis or repair can lead to more extensive damage. This is a known weak point in these engines and should be addressed promptly when symptoms appear.

Thanks for sharing your experience. The symptoms definitely match what I experienced with my SQ5. Really helpful to know the turbo actuator was the culprit in your case, since my boost pressure issues have been driving me crazy. Can you remember roughly how much the repair cost in total? Also, has everything been running smoothly since the fix, or have you noticed any other turbo-related problems? Just want to make sure I budget properly and know what to expect long-term.

After getting the work done at a turbo specialist, the boost leak issue was completely resolved. Total cost came to 250 Euro for replacing the faulty electrical bypass valve. The boost pressure actuator fault that triggered the warning light cleared immediately after the repair. The car has been running perfectly for the past 6 months, no more power loss, strange noises, or boost control problems. Fuel consumption returned to normal levels and the engine idles smoothly again. The boost pressure readings have remained stable during all driving conditions. Getting the actuator valve fixed promptly was key to preventing more expensive turbo damage. The specialist confirmed that leaving boost control issues unaddressed often leads to complete turbo failure. Based on this experience, investing in proper diagnosis and repair early on saved money in the long run. The turbo system has given zero issues since the fix, and performance feels like new again. No warning lights or boost-related problems have returned.

Thanks for the input. After reading about your experiences, I took my SQ5 to a different specialist who properly diagnosed the turbocharger issues. The boost control system needed work, just as suspected. The repair bill came to 280 Euro for parts and labor. They found a failing actuator and some worn seals causing the boost leak. The mechanic showed me the damaged parts and explained everything clearly, which was refreshing after my previous experiences. The turbo system is now working perfectly, no more whistling sounds or power issues. Fuel consumption is back to normal and the engine runs smoothly at idle. The check engine light cleared right after the fix and hasnt come back. Really glad I got this sorted before it turned into a bigger problem with the turbocharger. The specialist mentioned waiting longer could have meant complete turbo failure. Money well spent for peace of mind and proper boost pressure.