Audi A6 TFSI Check Engine + VANOS Issues Rising

I had a similar issue with my A4 2.0 TFSI from around the same generation. The variable timing system showed identical symptoms, check engine light, increased fuel consumption, and occasional engine misfire during cold starts. After some diagnostic work, the workshop confirmed a VANOS failure caused by a faulty camshaft solenoid valve. The repair involved replacing the inlet solenoid and checking the electrical connections. Total cost was around 250 Euro including parts and labor. Since the fix, fuel consumption returned to normal and the check engine light hasnt returned. Based on my moderate experience with these engines, these symptoms often point to variable timing issues, but proper diagnosis is crucial. Could you share: Build year of your A6, Current mileage, Any other symptoms like rough idle or drop in power, Any diagnostic codes you might have pulled This information would help determine if your case matches what I experienced and whether you might be facing the same VANOS system problem. The sooner you address this, the better, running with a faulty VANOS can lead to additional engine damage if left unchecked.

My A6 has 142818 KM on the clock with the last full service done just 2 months ago. Despite the recent service, I am still experiencing these issues. The engine misfire is most noticeable during cold starts, and the check engine light comes on intermittently. The variable timing problems seem to get worse when the engine is warm. Looking at the diagnostic codes, they point to camshaft timing issues which reinforces my suspicion about VANOS failure. I will make an appointment with a workshop this week to have it properly diagnosed. Thanks for sharing your experience with a similar issue, the repair costs you mentioned seem reasonable compared to what I was expecting.

Thanks for the follow-up. Given the mileage and symptoms you described, this definitely aligns with my experience. The low power during warm operation and cold start misfires are classic signs of inlet camshaft timing issues. One thing to note, when my A4 had these problems, we also discovered some oil sludge buildup in the variable timing components, which contributed to the failure. Since your car just had a service, check what oil grade was used. The wrong oil specification can accelerate VANOS wear. In my case, the timing chain tensioner also showed wear when they inspected the variable timing system. While not critical at that moment, I opted to replace it preventively since they were already working in that area. Added about 150 Euro to the total but gave peace of mind. The diagnostic codes you mentioned match what I encountered. Just ensure the workshop checks the entire variable timing assembly, not just the solenoid. Sometimes oil passages can be blocked, causing similar symptoms even with a new solenoid. The 142k km mark is typical for these issues to surface. Mine started showing problems around 138k km, so the timing makes sense.

Thank you for the detailed insight, this information matches my situation perfectly. The oil sludge issue you mentioned is particularly interesting since my engine has been using a bit more oil than usual lately. I will definitely have them check the oil passages and timing chain tensioner while they are working on the VANOS system. The inlet camshaft timing problems seem to follow the exact pattern you described. My check engine light actually came on again this morning during my cold start, accompanied by the usual engine misfire. The symptoms getting worse with a warm engine really had me worried, but knowing this is a common issue at this mileage is somewhat reassuring. I will make sure to request a complete inspection of the variable timing assembly when I take it in. Better to address any related issues now rather than facing another repair soon. I have scheduled the appointment for next week, and I will make sure to specify all these points to the workshop. The total cost including the tensioner replacement still seems reasonable for preventing future problems.