konstantinschwarz4
Sienna hybrid hissing sound on acceleration
Summary of the thread
A 2023 Sienna hybrid with 125,000 km was experiencing a loud hissing sound during acceleration, a check engine light, and poor fuel economy. The issue was suspected to be an air intake leak, possibly around the intake hose. After inspecting with soapy water and noticing bubbles, it was confirmed that the intake hose had a split. Replacing the hose resolved the problem, eliminating the hissing sound and restoring normal fuel economy.
Did this summary help you solve your problem?
4 comment(s)
konstantinschwarz4 (community.author)
Thanks! Was the hissing constant, or only under load? I'm trying to pinpoint it exactly. Also, did you notice any difference in engine sound besides the hiss?
gretasteel7
Only really noticeable under load, like accelerating or going uphill. The engine sounded a bit rougher too, like it was working harder than it should. Get it checked out, a leak like that messes with the fuel-air ratio. Could damage the catalytic converter.
konstantinschwarz4 (community.author)
Appreciate the advice! Took it to the shop – turns out the intake hose had a split. New hose, cost me 100€, and it's running smooth again. No more hissing, and the fuel economy's back to normal. Thanks for pointing me in the right direction!
rmh_community_comment_box_header
community_crosslink_scanner_headline
community_crosslink_scanner_intro
community_crosslink_scanner_title
community_crosslink_scanner_price
community_crosslink_rmh_headline
community_crosslink_rmh_intro
community_crosslink_rmh_title
community_crosslink_rmh_subtitle
community_crosslink_rmh_brand
TOYOTA
community_crosslink_rmh_model
SIENNA
gretasteel7
Hissing and poor mileage? Sounds familiar. I had a similar issue on my Sienna. Check all your vacuum hoses connected to the intake manifold and throttle body, especially the one connecting to the air filter housing. Could be a crack or loose connection.