Loud high-pitched electric-sounding whine from front of car
 

I have noticed when I turn the car off there is a loud electric-sounding whine coming from the front of the car for 5-10 seconds after turning it off. Today I changed the oil and had the radio on and the engine off and the entire time I was under the car I could hear this very loud high-pitched whine coming from around the area of the transmission. The frequency seems to go up and down slightly but the sound is constant. Any idea what this could be?

Cooling fan lingering on for a few seconds??

I also have a hum that lasts a few seconds when the car is shut off. There is another thread here that speculates the noise is caused by a pump in the brake system that runs if there is air in the brake lines. Some have said that the noise is covered in the manual, but I couldn’t find it.

Yeah...this noise was loud and constantly present for the entire 45 mins it took me to change the oil filter and oil. I was listing to the radio so the aux power was on and the engine was off and cold. Laying under the car looking up at the bottom of the transmission it sounded like it was coming from somewhere above the transmission - could've been from the area of the fan but not sure why the fan would be on and if that's the noise there's definitely something wrong with the fan because no fan was turning.

Hmmm....thanks the input...the mystery continues!

Could you hear it inside the cabin? Maybe seat fans? Can you turn on aux power and repeat the noise?

Nope...whatever it is it's clearly coming from the engine bay....its a constant high-pitched almost radio-static sound with a slightly oscillating frequency. I'll try and get some audio later.

Why not just take it to the dealer, let them check it.

Well to be honest because I've invested 5 min of my time asking this question here and if someone could give me a plausible reason why this sound is normal then I don't have to spend hours of my life going to the dealership.

Other than normal engine noise, my RX doesn't make any noise while idling. So if yours is as loud as you say, there's no way it's normal.

Sigh...I only notice it when the engine is OFF...either after turning the engine off (happens for a few seconds) or with the engine off and the aux power on (happened constantly for 45 mins).

When I turn off my car in a quiet garage, I hear a humming noise (fan, pump, servo) coming from under the hood. It lasts about 6 seconds or so. I also get a very quiet hum from the headlights until they go off. I get pretty much the same noises from both my 2016 and 17 RX’s.

I have not been able to find an explanation for the humming noise after shutdown in the manual, or on this forum. One thread here suggests that the noise is related to a pump in the brake system running because of air in the line. I don’t think so. I believe the noise is something simple and normal.

Of course the vent pump coming on five hours after shutdown always surprises, and scares me.

maybe the Horn is going bad and or Key Less entry Buzzer... those are in the engine bay

My car makes no noise when I shut it off, nothing. Several posters have said their cars make some sort of humming noise for a few seconds so that could be normal. If yours makes the noise the entire time you have it in accessory mode, that's not normal.

High pitched sound
 

My car also started making a high pitched sound when I turn it off. It lasts 5-10 seconds just as mentioned previously. It makes me think something needs tending to but there are no lights on the display panel to indicate any problem so I also have no idea what it relates to.

Both my cars 13 ES and 18 RX make the same noise. Mine only happens when the headlights are on, then the sound stops when the lights turn off. Nothing to worry about.