Audi Q3 Turbo Issues: Symptoms and Common Fixes

Had a similar situation with a 2013 Q5 2.0T last year. I have some experience working on turbo-related issues, though I usually leave complex diagnostics to professionals. The symptoms you describe match what I experienced, reduced power, increased fuel consumption, and that frustrating turbo lag. Initially thought it was the boost controller playing up, but the workshop diagnosed a faulty vacuum switching valve. The pressure drop was causing inconsistent boost control. The repair was straightforward once properly diagnosed. Total cost was 140 Euro including parts and labor. The workshop showed me the old part, it was completely worn out and causing irregular pressure readings. Before suggesting specific solutions, could you share: Any unusual sounds when accelerating? Does the power loss happen at specific RPM ranges? Have you noticed any whistling noises, particularly during boost? What error code is showing on the ECU? These details would help determine if your issue is identical to what I encountered. Worth checking if theres compressor surge under heavy acceleration, this can be a telltale sign of boost control issues.

Thanks for your insight. My car has 68167 KM and had its last service 3 months ago. There is a faint whistling noise when accelerating hard, especially between 2000-3000 RPM. The pressure sensor readings are erratic according to my OBD scanner, showing P0236 code. Been experiencing these symptoms for about 2 weeks, and the boost pressure drops significantly under load. The intake manifold pressure seems normal at idle, but fluctuates wildly during acceleration. No obvious vacuum leaks that I can spot. The bypass valve appears to be functioning, but the sound it makes seems different from usual. Will definitely get it checked professionally, but wanted to understand if this matches what you experienced with your repair.

Thanks for those additional details, they actually match my Q5 symptoms pretty closely. The P0236 code and whistling noise between 2000-3000 RPM were exactly what I experienced. The inconsistent boost readings on my OBD scanner were also similar, particularly during acceleration. After getting it fixed, I learned the erratic pressure readings were related to a failing boost solenoid, which was causing irregular pressure control and that distinctive whistling sound. This explained both the engine performance issues and the increased fuel consumption I was seeing. My car had slightly higher mileage (around 85000 KM) when this happened, but the repair process was the same. The vacuum leak from the faulty solenoid was causing the compressor surge symptoms you described, especially that unusual bypass valve sound. Quick tip: If your diagnostics show fluctuating boost pressure like mine did, its probably worth having the boost control system checked first, rather than replacing parts individually. The complete diagnosis and repair in my case prevented turbo lag issues from recurring. The early warning signs you caught should help prevent any potential damage to the turbo system. If its the same issue I had, you should be looking at a relatively straightforward fix.

Thanks for the detailed follow-up about your Q5 experience. Your description of the boost solenoid failure matches what I am seeing. The whistling noise and boost pressure fluctuations at those specific RPMs are remarkably similar. While my mileage is lower at 68167 KM, the symptoms align perfectly, especially the erratic pressure readings and that P0236 code. What you mentioned about the compressor surge during acceleration really helps confirm my suspicions about the boost control system. The turbo lag and pressure drop characteristics seem identical to what you experienced. My bypass valve is likely behaving oddly for the same reason yours did. Based on your repair costs of 140 Euro, this seems like a reasonable fix that wont break the bank. I will get it to a workshop this week to have them check the boost solenoid and vacuum system first, rather than replacing unusual parts. The engine performance issues you described clearing up after the repair gives me confidence this is the right path forward. Really appreciate you taking the time to share your experience, as it helped narrow down the likely cause. I will update once I get it diagnosed and repaired.