Audi A3 Turbo Issues: Hissing and Power Loss Alert

I had a very similar issue with my 2015 Audi A4 2.0T. As someone with some hands-on experience working on cars, I initially thought it might be something more serious, but it turned out to be relatively straightforward. The symptoms you describe match exactly what I experienced, the whistling noise and power loss were quite concerning. After taking it to the workshop, they diagnosed a faulty connection at the charge sensor and air temperature sensor assembly. The airflow sensor readings were inconsistent due to a damaged wire connection at the air intake. The fix involved replacing the wiring harness connector and properly securing the air temperature sensor connection. Total repair cost was 95 Euro, which included diagnostic time and parts. Before spending money though, you might want to check: 1. Visual inspection of all connections around the air intake system 2. Look for any loose or corroded wiring near the charge sensor 3. Check for obvious damage to the sensor housing Could you share: Current mileage on your A3? Any recent work done on the engine? Are these symptoms constant or intermittent? Have you noticed any changes in fuel consumption? This information would help determine if your issue is identical to what I experienced or if there might be other factors involved.

Thanks for sharing your experience. My vehicle has 8346 KM and just had its regular service last month. The temperature fluctuation issues started appearing intermittently at first but have become more frequent over the past week. The automotive sensor readings are particularly erratic when the engine is warm. After checking the forum history, I did a basic inspection of the air intake area and noticed some play in the connector housing near the temperature gauge assembly. Fuel consumption has increased by about 15% since these symptoms started. Based on your feedback, I will have the wiring connections checked first before replacing any parts. The whistling gets louder especially during highway acceleration. Would testing the charge air temperature sensor while the engine is cold vs hot help identify if this is truly the root cause?

Thanks for those additional details. Your symptoms align perfectly with what I experienced, especially the increasing frequency of the temperature fluctuations and that distinctive whistling during acceleration. When I dealt with this on my A4, I learned that testing the charge sensor readings at different temperatures was actually crucial for diagnosis. The temperature sensor showed normal readings when cold but became erratic once the engine warmed up, exactly like your case. The play you noticed in the connector housing is a major red flag and matches what I found on mine. The 15% increase in fuel consumption also tracks with my experience. In my case, the faulty temperature sensor readings were causing the engine management system to run a richer fuel mixture as a safety measure. Quick tips from my experience: 1. Check if the connector housing has any hairline cracks 2. The engine sensor wiring often develops issues right where it bends near the intake 3. Look for signs of heat damage on the airflow sensor wiring insulation One thing I noticed with mine, the whistling was actually air escaping through the damaged connector seal, not a turbo issue as I initially feared. Given your low mileage, I strongly suspect you have the same connector issue I had rather than a failed sensor unit itself. Consider getting the diagnostic logs checked specifically for temperature sensor reading patterns. This helped pinpoint the exact issue in my case and saved time troubleshooting.

I appreciate all the detailed feedback, especially about testing the sensor readings at different temperatures. After checking the connector housing more carefully following your advice, I found a small crack exactly where you mentioned, right at the bend near the intake. The airflow sensor wiring looks intact, but the connector seal definitely shows signs of wear. I checked the temperature gauge readings this morning during a cold start versus after 20 minutes of driving, and the difference is significant. The air temperature readings become extremely inconsistent once the engine warms up. I will focus on getting the connector housing and seal replaced first, rather than immediately replacing the entire charge air temperature sensor assembly. The symptoms match your experience so closely that I am confident this is the right path forward. The intermittent nature of the temperature fluctuations makes more sense now, knowing it is likely a connection issue rather than a complete sensor failure. Will update once I get the connector replaced and see if this resolves both the whistling and the engine performance issues.