Matrix VANOS and Fuel Consumption

I also drive a Matrix and had similar symptoms a while back. The check engine light was on, and my fuel economy dropped. Did you notice any changes in the engine's sound or performance besides the increased fuel consumption? Also, have you checked the timing chain? A stretched or worn timing chain can sometimes trigger VANOS-related codes.

Thanks for the quick reply! I haven't really noticed any significant changes in the engine sound, although it might be a bit rougher than usual. Regarding performance, it feels a bit sluggish, especially when accelerating. I haven't checked the timing chain myself – I'm not really sure how to do that. Is it a difficult task, and is it something I can do myself, or should I leave it to a professional?

Given your description and lack of experience, I'd strongly suggest taking it to a reputable mechanic. The timing chain is a critical component, and messing with it without proper knowledge can cause serious engine damage. It does sound like a VANOS issue. In my case, it turned out to be a faulty solenoid valve. If it is that, the mechanic should be able to diagnose it quickly.

Thank you so much for your advice! I took it to my local mechanic, and you were spot on – it was indeed a faulty camshaft solenoid valve causing the VANOS issue. They replaced it, and the check engine light is gone, and my fuel consumption is back to normal. The total repair cost was around 250€ I really appreciate your help in pointing me in the right direction!