That hose appears to be a ventilation hose connected to the PCV valve.

VENTILATION HOSE. 2020 toyota Highlander | Toyota

2020 toyota Highlander VENTILATION HOSE

parts.toyota.com

 

This helps a lot thank you.

 

Yes! I am narrowing this down PCV Valve Noise - the noise sounds just like my noise...

Why does my PCV valve make noise?

A noisy PCV valve usually means too much air is passing through it, not a problem with the valve. An air leak in the block will cause the PCV system to pass too much air. This can also create a lean misfire in the cylinders closest to where the PCV connects to the intake manifold, bringing on a check engine light.

 

Thanks. I will be picking up a pcv valve tomorrow since they are so cheap and easy to replace. My guess is it won't work but will try just to rule this out. Yes, thank you I think you are right about some sort of vacuum leak.

 

This is just an update for the next person who has the same problem as me. I read this on the youtube video above where there was a long thread regarding this exact problem but with a different auto.

I like this comment, "The noise is a cause of vacuum being at a specific level so the valve begins to "ring". Nothing dangerous if the car is running fine and is not consuming an excessive amount of oil. My car consumes almost nothing at all during change interval and the engine is running more than perfect"

This thread also leads me to believe that the pcv valve change won't work. I will let you know later. Again this whole thread now is just me paying it forward for the next person who has to deal with this problem. My next step is looking at error codes with my cheap computer and perhaps running propane to find a potential leak.

I sure received a lot of problems from this auto. I will leave this for another thread about my dealings with dealer trying to get out of warranty regarding parking sensors and a useless executive office for Toyota USA.

Adding another video with a similar sound to my auto. Picking up genuine Toyota part from a dealer. I am really looking forward to seeing what the result is either way

Another buzzing sound video

 

So I bought the new pvc valve and promptly broke it by overtightening. The good news is the break was clean and I was able to remove with pliers. I put the old one back...but before putting back I started up the auto and put my thumb over hose and felt suction. Then I retightened until I received some resistance and tightened a little more and stopped this time.

Good news so far after driving a bit...no more buzzing / rattling. I will continue to monitor to see if it comes back. I see this break as a success because I learned...even if some of a part is metal don't assume the rest is...be sure there is no plastic threads next time.

I enjoyed walking past the service area which was full of people looking like zombies waiting for their auto to be fixed / serviced. I hate sitting in there and watching the cheerful service person come in and say out loud to customers such and such needs to be fixed.