RS5 VANOS Issues Trigger High Fuel Consumption

I had a very similar issue with my 2011 S5, also with a check engine light and increased fuel consumption. With some basic car repair experience, I initially tried diagnosing it myself. The symptoms matched perfectly with what you are describing. After multiple engine misfires, I took it to a workshop where they confirmed a faulty VANOS solenoid on the inlet camshaft. They found the solenoid was not getting proper power supply, causing irregular valve timing. The total repair cost was 250 Euro, which included diagnostics and replacement of the defective component. The repair resolved both the check engine light and the high fuel consumption issues. Before suggesting specific solutions, could you share: Have you noticed any rough idling? Does the engine make any unusual noises, especially during cold starts? Have you scanned for error codes? How many miles/kilometers are on the engine? When was your last oil change? Oil sludge can sometimes contribute to VANOS issues. This information would help determine if your issue is similar to what I experienced and could save you time and money at the workshop.

Thanks for the feedback. The engine has 194658 KM and had its last service just 2 months ago. The issue started showing up last week. Yes, there is some rough idling, especially when the engine is cold. I hear a slight rattling noise from the timing chain area during cold starts which goes away after warming up. I did scan for codes which showed P0011, Intake Camshaft Position Timing Over Advanced. The low power is most noticeable when accelerating from a stop. My fuel consumption has increased by about 15% based on my calculations. I originally thought it might just need an oil change, but since that was done recently, I suspect the VANOS solenoid could be the culprit causing these engine misfires.

Thanks for providing those details. Having experienced almost the exact same symptoms with my S5, I am now even more convinced we dealt with similar VANOS failure issues. The P0011 code, combined with the timing chain noise during cold starts, strongly points to a failing VANOS solenoid. The 15% increase in fuel consumption matches what I experienced, and the low power during acceleration is another classic symptom of variable timing problems. In my case, debris in the VANOS solenoid was causing irregular camshaft timing. While the recent oil change rules out oil-related issues, the high mileage suggests the VANOS components might be showing natural wear. A few quick checks you can do: Listen for timing chain rattle intensifying during warm-up, Monitor if power loss gets worse in cold weather, Check if the rough idle improves as engine warms up Based on my repair experience, I would recommend getting the VANOS solenoid replaced soon. Delaying could lead to more serious engine timing issues. The repair should be straightforward for any qualified shop, similar to the 250 Euro job I had done. Would you like me to share more specific details about the repair process I went through?

Having listened to the discussion, I feel more confident about my next steps. The matching symptoms with your case, especially the P0011 code and the cold start timing chain noise, really help confirm my suspicions about the VANOS solenoid being the issue. The check engine light combined with that specific error code, plus the rough idle and increased fuel consumption, all point to what you experienced. Since my recent oil change rules out oil sludge buildup as a cause, focusing on the inlet camshaft and VANOS system makes sense. Your repair cost of 250 Euro gives me a good baseline for what to expect. I will get it looked at this week, no point risking more serious variable timing problems by waiting. The fact that your fix resolved similar issues is encouraging. Just one last question, did you notice any improvement in performance immediately after the repair, or did it take some time for the engine to adjust to the new VANOS solenoid?