Audi Q5 VANOS Issues Causing High Fuel Consumption

As someone with some repair experience, I dealt with a similar issue on my 2016 Audi A4 2.0T. The check engine light came on, accompanied by increased fuel consumption and rough idling, which turned out to be related to a faulty variable timing solenoid. The timing chain system in these engines is quite sensitive to oil sludge buildup, which can affect the VANOS solenoid operation. After taking it to a workshop, they diagnosed the problem through a complete diagnostic scan and physical inspection of the solenoid electrical connections. The repair involved replacing one faulty camshaft solenoid valve and cleaning the surrounding area to prevent future issues. Total cost was around 250 Euro, including parts and labor. The fix resolved both the check engine light and the fuel consumption problems. Before suggesting more specific advice, could you share: Any unusual engine sounds? When was your last oil change? Are you experiencing rough idling? Have you scanned for specific error codes? This information would help determine if your issue matches what I experienced and could save you time and money in diagnosis.

Thanks for the reply. My mileage is currently at 118441 KM and the last oil change was done during the routine service 3 months ago. The engine does make a slight rattling noise during cold starts that goes away after warming up. I noticed the rough idling mainly when stopping at traffic lights. The error code I got was P0011 which points to the intake camshaft timing being over-advanced. The engine misfire is most noticeable during acceleration. One mechanic suggested it could be a timing chain issue but wanted more diagnosis before confirming.

Thanks for providing those details. The P0011 code and symptoms you're describing are very similar to what I experienced with my A4 before the repair. The rattling noise during cold starts combined with rough idling and engine misfire during acceleration strongly suggests VANOS failure, rather than a timing chain issue. In my case, the mechanic initially suspected the timing chain too, but further testing showed the variable timing system was the actual culprit. The rattling noise you mentioned during cold starts is particularly telling, this was also present in my car and disappeared after the VANOS repair. Given your recent oil change, oil quality likely isnt the issue. However, the mileage on your car matches when these problems typically start showing up. When my VANOS solenoid was replaced, the mechanic found significant debris accumulation affecting the variable timing operation. Based on the low power issues and engine misfire you're experiencing, I recommend: 1. Getting the VANOS solenoid tested specifically 2. Having the oil passages to the VANOS unit checked for blockage 3. Checking the timing chain tensioner condition while they're in there My total repair ended up around 300 Euro when they found additional cleaning was needed. The symptoms completely resolved after the fix, and fuel consumption returned to normal within two tanks.

Thanks for sharing those repair details and costs. The symptoms you experienced with your A4 match what I'm seeing. The cold start rattling and P0011 code definitely point toward the inlet camshaft timing system rather than a major timing chain problem, which is somewhat reassuring. I've scheduled an appointment next week to have the VANOS solenoid tested and cleaned first, since that seems to be the most likely cause based on the engine misfire and low power issues I'm experiencing. They'll also check the timing chain tensioner while they're working on it, just to be safe. The estimate I received was around 350 Euro for parts and labor, which seems reasonable compared to your repair costs. I'll make sure they thoroughly clean the oil passages to prevent future problems. Hopefully this resolves the rough idling and gets my fuel consumption back to normal levels. Will update once I have the work done and can confirm if fixing the variable timing system solved all the issues.