PetrinaWag
i30 Hissing Sound and Fuel Consumption
Summary of the thread
A 2013 Hyundai i30 owner reported increased fuel consumption, a persistent check engine light, and a loud hissing sound during acceleration. Suspecting a vacuum leak, they considered a cracked intake hose as a potential cause. A fellow owner suggested checking hoses connected to the intake manifold and air filter, and recommended a smoke test to locate the leak. The issue was confirmed to be a cracked intake hose, which was replaced, resolving the problem.
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4 comment(s)
PetrinaWag (community.author)
Thanks for the tip! I'll give those hoses a really good look. I checked the error codes, and it gave me a P0171 code, which means 'System Too Lean (Bank 1)'. I realize that it's pointing towards a lean mixture, meaning too much air and not enough fuel, that's why I'm leaning towards a leak somewhere. Could you tell me what fixed the problem for you back then?
davidblade8
That code confirms a leak after the mass airflow sensor. In my case, it turned out to be the intake hose connecting to the turbocharger - it had a small crack on the underside that was almost impossible to see without removing it. I'd recommend taking it to a mechanic with smoke machine, which will help to confirm for sure where the leak is located and avoid unnecessary spending.
PetrinaWag (community.author)
You were spot on! I took it to a local shop, and they confirmed it was indeed a cracked intake hose. The smoke test made the leak immediately obvious, and they replaced the hose for about 100€. The hissing is gone, the check engine light is off, and the fuel consumption seems back to normal. Thanks a bunch for your help!
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HYUNDAI
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I30
davidblade8
I had a similar issue with my i30, although with different mileage. Higher fuel consumption and a hissing sound are classic symptoms of an air intake leak. Check all your hoses connected to the intake manifold and air filter. Sometimes it can be a split or crack that's hard to see unless you really get in there and inspect them. Did you check the engine code from the check engine light?