RS6 Flashing CEL + Stalling Points to EVAP System

Had similar issues with my 2007 RS4 last month. The engine light came on and idle got rough, turned out the EVAP system was completely clogged. The pressure sensor was giving false readings because dirt and debris blocked several vacuum hoses. The real problem was a loose gas cap that allowed debris to enter the system over time, combined with carbon buildup in the purge valve. The main ventilation line to the charcoal canister was almost completely blocked. This is a serious issue since it can damage the fuel system and cause poor engine performance. The repair involved: Complete EVAP system inspection, Cleaning all ventilation hoses, Replacing the purge valve, Installing a new gas cap, Clearing fault codes Best approach is finding a shop specializing in German performance cars. Request they do a smoke test of the EVAP system first, this will reveal exact location of any leaks or blockages. Make sure they check both the purge and vent valves, as these commonly fail on these models. This isnt a quick fix job, proper diagnosis and repair takes time to do right. The symptoms you describe match exactly what happens when the EVAP system fails to maintain correct tank pressure.

Thanks for sharing your experience. Your EVAP system issue sounds identical to what I dealt with on my RS6 last year. The check engine light and rough idle turned out to be from a failing purge valve and blocked ventilation lines. The description of the repair process you outlined matches what my mechanic did too. Was wondering how much the total repair ended up costing you? Also curious if you had any emission system related problems pop up since getting it fixed? Mine has been running great but I notice the gas cap sometimes needs an extra turn to click properly now.

Had the repair done about 3 weeks ago and it completely resolved the tank ventilation valve issues. The automotive repair shop found several seriously clogged hoses in the EVAP system that were causing the pressure sensor to malfunction. The total came to 175 Euro for cleaning out the ventilation lines and getting everything working properly again. No emission system problems since the fix, the engine idles smoothly and the check engine light has stayed off. The purge valve is working as it should now. Regarding your gas cap concern, might be worth having the threading checked. A proper seal at the gas cap is crucial for the EVAP system to maintain correct pressure.

Thanks for the input. Finally got this sorted at a specialized shop. The engine light issue was exactly what you described, clogged EVAP system lines and a faulty purge valve. Total bill came to 230 Euro which included a full system cleaning and new parts. The mechanic I found actually specializes in emission systems and did a thorough smoke test before starting repairs. He showed me all the blocked areas and explained how the tank ventilation system works. Much better experience than my previous shop. Engine runs perfect now, no more stalling or rough idle. They also replaced my gas cap since the old one was causing some of the ventilation problems. All warning lights are off and the EVAP system is working like new. Worth every cent to get it done right by someone who knew what they were doing.