Audi A8 Turbo Failure Symptoms Point to Boost Sensor

I had a comparable issue with my 2020 Audi A6 diesel last month. As someone with moderate experience working on cars, the symptoms you describe sound very familiar. The check engine light came on, and I noticed similar problems, especially the power loss and strange noises from the turbo system area. The boost sensor readings were inconsistent, which pointed to a potential pressure sensor issue. Took it to my workshop where they diagnosed a loose connection in the wiring harness connected to the boost pressure sensor. The repair involved checking all cable connections and replacing a damaged plug. Total cost was 95 Euro for parts and labor, which was reasonable considering the symptoms. The fix resolved all issues, no more engine light, proper power delivery restored, and normal boost sensor readings. Before suggesting more specific solutions, could you share: Current mileage on your A8, When did these symptoms first appear, Have you noticed any correlation with weather conditions, Any recent work done on the turbo system, Are there any other warning lights besides the engine light This information would help determine if your issue matches what I experienced or might be something different in the turbo system.

Thanks for sharing your experience. My A8 has 77252 KM and just had its annual service last month. After reading your description, I think we might be dealing with different issues. My whistling sounds are much more pronounced, suggesting a possible boost leak in the intake manifold rather than just a sensor problem. Also tried checking the boost pressure sensor connections myself but they seem tight. In my case the symptoms started suddenly during highway driving and have been consistent regardless of weather. The turbocharger problems are getting worse, especially the power loss during acceleration. Would be interested to hear if anyone else has experienced similar turbo system issues that turned out to be more than just sensor-related.

Thanks for providing those details. After reading your symptoms more carefully, I agree this sounds different from my sensor connection issue. The pronounced whistling combined with power loss and consistent symptoms points more toward a physical problem in the turbo system rather than just sensor readings. On my previous A6, I actually encountered a similar situation about 6 months before the sensor issue. The loud whistling turned out to be a split intercooler pipe causing a major boost leak. The intake manifold was fine, but the leak was robbing the turbocharger of pressure, causing similar power loss symptoms. The repair involved: Pressure testing the entire turbo system, Replacing the cracked pipe, Installing updated clamps, Checking the wastegate operation Total repair cost was 485 Euro, which included parts and labor. After the fix, the engine light cleared and performance returned to normal. Given your symptoms are getting worse, I recommend having the workshop do a full pressure test of the turbo system. A boost leak test would quickly identify if there are any breaks in the pipes or connections between the turbocharger and intake manifold. Better to address it soon before it potentially causes more extensive damage.

Thanks everyone for the detailed responses. After reading through the suggestions, especially about the intercooler pipe issue, I scheduled an appointment with my shop for next week. The whistling from the turbocharger area has gotten even louder since my last post, and the air intake system definitely seems to be losing pressure somewhere. My gut feeling is pointing toward a significant boost leak rather than just a faulty pressure sensor, given how the symptoms keep getting worse. Will update once the shop performs the pressure test on the entire turbo system and checks the intake manifold connections. Hoping its just a cracked pipe like mentioned and not a more serious turbocharger issue. Really appreciate all the detailed experiences shared, helps narrow down the potential problems before heading to the shop. Planning to have them do a complete inspection of all turbo-related components while they have it apart. Better to catch any other developing issues now rather than dealing with multiple repairs later.