Audi S4 Crankcase Valve Issues Slash Engine Power

Had similar symptoms on my 2011 Audi S5 with the 3.0T engine. The PCV system malfunction started with white smoke during acceleration and noticeable power loss. The maintenance revealed a failed crankcase ventilation valve, which was causing excessive pressure buildup in the system. The smoke occurs because oil vapor gets pushed into the intake when the PCV valve fails. This is quite serious as it can lead to increased oil consumption, carbon buildup on valves, and potential turbo issues if left unaddressed. The leak can also cause rough idle and vacuum-related problems. The repair requires replacing the complete PCV assembly and checking connected components like vacuum lines and seals. In my case, the oil separator was also contaminated and needed replacement. This is not a quick fix, the intake manifold needs to come off for proper access. Watch out for shops trying to just clean the system instead of replacing components. The proper fix requires new parts since cleaning rarely resolves the underlying valve failure. Make sure they pressure test the system after repair to confirm no remaining leaks.

Thanks for sharing your experience. Had almost identical issues with my S4 last year. Really helped to know what we are dealing with here. Did the fix fully resolve the smoke and emissions issues for you? Would be good to know the repair cost you paid and if any other problems showed up afterwards. My mechanic quoted me but Im trying to figure out if its reasonable.

Thanks for asking about the results. The PCV valve replacement completely fixed all the smoke issues and restored normal engine performance on my S4. The crankcase ventilation system now works perfectly, no more white smoke during acceleration or power loss. The total maintenance bill came to 360 Euro for parts and labor, which resolved the defective valve and included testing the entire system. The repair price was fair considering the work involved in accessing and replacing the PCV components properly. After six months of driving, no additional problems have appeared. The engine runs smoothly with proper crankcase pressure regulation. Just make sure your mechanic does a thorough check of all connected components while they have everything apart. Regular valve cleaning as part of routine maintenance can help prevent future issues.

Thanks for the input. Finally got it fixed last week after checking a few shops. Found a specialist who really knew these engines and the common ventilation system issues. The repair took about 4 hours. They replaced the valve, checked all connected parts, and did a full system pressure test. Total came to 395 Euro, bit more than expected but worth it for proper diagnostics and genuine parts. What a difference after the fix, no more smoke, power is back to normal, and engine light cleared right up. Engine runs so much smoother now during acceleration. Was definitely worth getting it sorted properly rather than trying quick fixes. Nice to have confirmation from others who dealt with similar problems. Really helped knowing what to expect during the repair process.