The searches IÂ’ve come across seem to all be people talking about the humming noise where the vehicle is running a systems check after the vehicle has been off a few hours. IÂ’ve heard that noise and am familiar with it and this is not the same noise. IÂ’ve got a 2023 4Runner with 8,000 miles and IÂ’ve heard this whining noise probably 15 times start the past month. The first few times was while I was sitting at a stop light. I thought steering pump, but when I turned my steering wheel while hearing the noise, it never changed. Then I started to hear it within a few minutes of shutting the vehicle off so I ruled out power steering pump and bearing or tensioner pulley. My next best guess is a vacuum leak? ItÂ’s coming from underneath the vehicle and seems like it is near the fuel tank. Is it a fuel pump noise? I couldnÂ’t post the video, so here is a link to hear the noise

IMG 2920 - YouTube

I havenÂ’t taken it to the dealer yet because this noise doesnÂ’t happen every time I turn the vehicle off. From past experience, they use not being able to recreate the noise as a reason to not fool with it. Thanks in advance!

I am having the same issue now. Did you find any solution to solve this whining noise?
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I think it is definitely something to do with the fuel system. a smoke test would probably find the leak. if it's not a leak could be the charcoal canister. do you have a check engine light, poor performance and mileage?

I typically leave the wife & kids at home & magically the whining stops.

Check if the noise changes with the fuel level. Does it get louder when the tank is full or low? Also, inspect the fuel lines for any kinks or damage.
A faulty fuel pump relay can cause whining noises. The EVAP system might also make strange noises if there's a small leak or the purge valve isn't working right. A smoke test can help find leaks in this system.