2017 V humming noise when ICE kicks in

pretty tough to diagnose over the internet, can you post an audio clip?

 

Is it engine or wheels/ suspension making the noise?
Humming is a unique description.
Many compare humming noises to tires and not mechanical ones.
Yes, diagnosing noises over the internet may be futile.
Yes, the check engine light indicates a current code, yet perhaps there is a stored code a robust reader will list.

If you are a DIY mechanic, jack up the car, have an assistant run the throttle, while you crawl around under the car and over the engine listening.
If a wheel /suspension noise this will be more difficult to find and may require an experienced suspension shop.

Lastly, hybrids do make noises a standard vehicle may not make.
Good hunting.

 

There is a low speed pedestrian warning - a high pitched tone produced by a speaker up front. Unless it is cv joint from your other thread.

Probably a misfire which causes a severe shake and rattle on a Prius. Normal misfires are frequent and bring up codes. Engine off to on misfires that clear up quickly can be an early head gasket leak. See if it keeps happening.

 

In my case, it's heat shields that rust out around the mounting holes. They then make a humming/buzzing sound when the ICE starts up and is still cold, though it usually goes away when the engine warms up and parts begin to expand, but this depends on how badly the shields have detached. I usually try to find the bad mounting points and remount the shield using a larger (stainless) fender washer to cover a larger portion of the heat shield.

 

I don't know if this is related, but I came across this thread because my 2017 Prius V recently started to make a noise, usually right when I accelerate enough for the ICE to kick on. It is most noticeable when I accelerate very gradually, just as the car transitions from EV to ICE. If I accelerate quickly, I usually don't hear it. I would describe the noise as a warbling sound. It's moderately high pitched, and cyclical, like a rather quick "whump, whump, whump." It does not continue for long, just until the ICE takes over. Then it goes quiet. I have also heard what sounds like the same noise occasionally when I am accelerating slowly in EV mode, and suddenly take my foot off the accelerator. In that scenario, it is not a cyclical noise. Just a single, momentary "whump." Don't know what to make of it. I've been searching the Internet, but all I seem to get is info about rattles. This is definitely not a rattle. Any ideas? Suggestions?