Audi VANOS Issues Drive Fuel Consumption Sky-High

Had a similar issue with my 2014 A6 3.0T last year, and I have some experience working on these engines. The symptoms you describe match what I dealt with, increased fuel consumption and persistent check engine light pointed to a VANOS system problem. The variable timing system failure was causing the engine to run inefficiently. In my case, it turned out to be a faulty camshaft solenoid valve. The repair involved replacing the solenoid and checking the entire VANOS system. Total cost was around 250 Euro for parts and labor. Before jumping to conclusions, could you share: Any engine misfire symptoms? Does the engine feel less powerful? Have you noticed any unusual noise from the timing chain area? What error codes is the check engine light showing? A proper diagnosis is crucial since VANOS failure symptoms can sometimes be confused with other issues. Worth checking if the timing chain is also affected, as these problems can be related. Getting the error codes read would help narrow down if its definitely a VANOS issue rather than something else. My workshop did a full diagnostic check before starting repairs, which I would strongly recommend. They found the solenoid was getting inconsistent power supply, leading to the variable timing system working incorrectly.

I had the diagnostic done at 189400 KM. Error codes showed P0011 and P0021, which confirm variable timing issues. No misfires yet, but definitely noticed reduced power, especially during acceleration. The engine does sound a bit rougher at idle. Also seeing oil sludge in the valve cover area when I checked, which might be contributing to the inlet camshaft problems. Will have the solenoids cleaned or replaced depending on their condition. The check engine light hasnt gone away even after clearing the codes. Planning to book it in next week and will update on the repair costs and what exactly needed replacing.

Thanks for the update on those error codes. Having dealt with similar issues on my A6, those codes definitely point to inlet VANOS timing problems. The oil sludge you mentioned in the valve cover is particularly concerning, this exact issue led to my variable timing problems getting worse before I addressed them. The rough idle combined with low power during acceleration matches what I experienced before the repair. Since youre not getting engine misfire codes yet, catching this early is good timing. In my case, waiting too long led to occasional misfires that developed later. Few things I learned from my experience: Make sure they clean the entire VANOS system, not just replace parts, Consider having the oil pickup tube checked for sludge buildup, The check engine light staying on after code clearing often indicates an active problem rather than a sensor issue My repair started with solenoid replacement but ended up needing more extensive cleaning of the variable timing components due to oil deposits. Total repair came to about 800 Euro, but prevented more costly damage. Would definitely recommend getting this sorted soon before it potentially affects other components. The timing chain should also be inspected while theyre in there.

Thanks for the input. Just got the car back from the workshop and wanted to share the outcome. The VANOS failure diagnosis was spot on, they found significant oil sludge affecting the variable timing system. Total repair ended up costing 920 Euro. They replaced both inlet camshaft solenoids and performed a complete system cleaning. The timing chain showed minimal wear so fortunately no replacement needed there. The low power issues are completely resolved and fuel consumption is back to normal. Main takeaways from this experience: Oil sludge buildup can seriously impact the VANOS system, Getting it fixed early prevented more extensive damage, Regular maintenance is key to preventing these issues, The workshop confirmed waiting longer could have led to engine misfires The check engine light is now off and staying off. Engine runs smooth at idle and power delivery is back to normal. Going to stick to a stricter oil change schedule to prevent future variable timing problems. Thanks again for helping confirm the diagnosis. Would have spent more time and money troubleshooting without the shared experiences here.