S5 Intake Manifold Symptoms Point to Flap Control Issue

Had similar symptoms on my 2020 Audi A5 TDI. The engine light came on followed by noticeable power loss and irregular engine behavior. The intake system was indeed the source, specifically the manifold flap control unit had failed. The repair involved replacing the entire intake manifold assembly because the flap control motor was integrated into the unit. This is actually a known issue that affects multiple VAG diesel engines. The symptoms you describe match exactly what I experienced, engine misfire during acceleration, increased fuel consumption, and that characteristic hissing sound from the intake area. The repair was significant but not critical if addressed promptly. Left unattended, it can lead to more serious engine damage and higher repair costs. The mechanic explained that when the flap control fails, it disrupts proper air distribution in the intake system, causing the engine management to run rich fuel mixtures as a safety measure. The fix took about 4 hours of labor, and the engine performed like new afterward. Would recommend getting it checked soon, as continuing to drive with these symptoms can potentially damage other components.

Thanks for sharing your experience. Really sounds identical to what I went through with my S5. The engine performance issues and air intake problems were driving me crazy until I got it fixed. Since you had the same manifold flap control problem, would you mind sharing what the total repair cost was? Also curious if you have had any other issues pop up since the repair, my engine misfire completely disappeared after the fix but always good to know what to watch out for.

Just got the invoice last week, the flap control repair came to 465 Euro total. The mechanic managed to fix the switch intake manifold control defect without needing to replace the entire assembly, which saved quite a bit of money. Since the repair, the engine has been running perfectly, no more misfires, hissing sounds, or airflow control issues. The fuel consumption is back to normal, and the engine light hasnt shown up again. The intake system is working exactly as it should. Its been about 8000 km since the fix, and I havent experienced any related problems. The engine performance is consistently smooth, especially during acceleration. Getting the intake manifold flap control fixed definitely solved all the original issues. Just make sure you go to a mechanic who really knows these engines, proper diagnosis of the flap control system is crucial for an effective repair.

I finally got the manifold flap control issue sorted out at the shop. Had to switch mechanics but found a specialist who really knew their stuff. They diagnosed the intake system problem in under an hour and confirmed your exact suspicions about the airflow control unit. Total repair came to 890 Euro, bit more than yours but they replaced some surrounding components showing wear. Engine performance is back to normal now. No more hissing sounds, the acceleration is smooth again, and fuel consumption dropped back to usual levels. Been about 3 weeks since the fix and put around 2000 km on it. Everything is running perfectly, no check engine lights or odd noises from the intake manifold. Really glad I got it sorted before it could cause any bigger issues. Thanks again for helping point me in the right direction with the diagnosis.