Etios Hissing and Fuel Consumption

Sounds familiar! I had something similar happen on my Etios. That hissing points to a vacuum leak for sure. Check all the hoses connected to your intake manifold, especially the intake hose between the air filter box and the throttle body. Are you hearing the hissing all the time or just when the engine is cold?

Thanks! So, a vacuum hose... That makes sense. I'll check those hoses first thing tomorrow. But what does the turbocharger do? And could the hose cause the check engine light to come on, too?

The Etios doesn't have a turbocharger, so you can rule that out. And yeah, a vacuum leak definitely triggers the check engine light because it messes with the air-fuel mixture. If you find a cracked hose, try replacing it yourself. Otherwise, just take it to a workshop. It's what I did. Good luck!

Awesome, thanks so much for the help! I took it to a mechanic and you were spot on – it was a leaking intake hose. Cost me around 100€ to get fixed. Fuel economy is back to normal and the hissing is gone!