RS6 Rough Idle Points to Air Valve Issue

As an RS4 owner, I encountered nearly identical symptoms. The check engine light and rough idle were caused by a damaged hose connection between the vacuum pump and air valve. The manifold pressure was inconsistent due to a small air leak, which directly affected the air supply to the engine. The stalling at idle is a classic symptom of this issue. When the engine management system cant maintain proper air intake levels, it struggles to keep consistent idle. These vacuum leaks often start small but can develop into more serious problems if left unchecked. The repair involved replacing the deteriorated hose and checking the entire vacuum system for additional leaks. This turned out to be a critical repair, as continued operation could have led to further engine management issues and potential damage to other components. The throttle body could be related, but in most cases with these symptoms, checking the vacuum lines and air valve assembly should be the first step. A proper diagnosis requires testing the manifold pressure and examining all vacuum connections. Suggest getting a full vacuum system inspection with particular attention to the connections around the air valve assembly. This is typically a straightforward diagnostic process for shops familiar with VAG engines.

Thanks for sharing your experience. My vacuum leak issue was also resolved by replacing hoses and checking the air supply system. Definitely sounds like we had similar problems with engine stalling at idle. Quick question: do you remember roughly how much the repair cost in your case? Also curious if youve had any other issues pop up since the fix? Been running great on my end but always good to know what to watch out for with these engines.

Glad to help with the comparison. After getting that air valve and vacuum hose connection fixed, my RS6 has been running perfectly smooth for the past 8 months. The total repair came to 175 Euro, which covered both the faulty hose replacement and a thorough check of the entire vacuum system. The rough idle and check engine warnings completely disappeared once the proper connection between the pump and valve was restored. No other vacuum leak or idle problems have surfaced since the repair. Its worth mentioning that the mechanic did a complete pressure test of all vacuum hoses while they had it apart, which probably helped prevent any future issues. The initial symptoms you described, especially the engine stalling at stops, matched my experience exactly, so its not surprising we had the same root cause. A properly sealed vacuum system is crucial for maintaining stable idle, so its good to hear your repair also sorted out the problems. Regular checks of these connections during maintenance can help catch any developing issues before they trigger check engine lights or idle problems again.

After dealing with those annoying idle problems and check engine warnings, I finally got my RS6 properly fixed. The repair turned out exactly like others mentioned, it was indeed a vacuum leak causing the rough idle. Found a different mechanic who really knew their stuff about these engines. They did a complete manifold pressure test and found the air supply issue right away. The old vacuum hose near the air valve was cracked, causing inconsistent throttle body response. The repair cost came to 190 Euro total, including full system testing and new hoses. Been driving for about 3 weeks now and the engine runs perfectly smooth. No more stalling at lights or check engine warnings. Really glad I got that second opinion rather than going back to the first shop. The new mechanic also showed me what to watch for in the future to catch any potential vacuum issues early.