Has it been over five hours for the sound to occur?

 

My 2019 trunk is silent when the car is turned off. I do greatly issue the electronic trunk open/close that was on my Lincoln.

 

I hear similar sounds from my '21 Avalon Hybrid that I heard from my '16 Corolla when turning the ignition off and on.
There are a number of electric motors, including the power steering, braking system, EVAP, etc...
Nothing loud or extended, just the occasional "whir".

 

Not to hijack (I did run a separate search to no avail) but when I open the driver's door on my 2019 Avalon Hybrid there is a very noticeable pump noise that seems to emanate from the front passenger side of the engine bay. Is that normal? If so does anyone know what it is?

 

That may be the ABS pump. In his video on doing brakes on a hybrid, CarCareNut talks about being careful not to do certain things when bleeding your brakes, and I think opening/closing the door was one of them.

 

Thanks cb91710, I truly appreciate it. I've only been lurking around here for a few weeks since my purchase but I've noticed that you've quite the knowledge base and give very reasoned and measured responses / advice, Thank You.

Lastly, I'll second The Car Care Nut's youtube channel, another great resource.

 

My Avalon lives in the driveway (wife's Silverado and our '79 MGB get the garage). Tonight,the wife is out of town, so I parked in the garage. I worked on my MGB for a few hours (new rear suspension going on). My Avalon was quiet. I went out two hours later, to make sure the entry door to the garage was locked (it was..) There was a noticable hum from under the rear of the car. I opened the trunk, no change. I started and stopped the car, the noise stopped. It a motor of some sort. The car was at the dealer the past few days to resolve my noise/fluttering issue, which has its own thread. If the car was in the drive-way, I wonder if it would have ran unnoticed all night? We have temps in the high teens here tonight, my guess is the battery would have run down pretty quickly. Guess I'll have to monitor this now.

 

These hybrids make weird noises. Mine does. I wouldn’t worry about it.

 

OP never coming back. @Warbird21 it's just the evap, read you manual for it.

 

Thanks Vangm25 - I never knew this happened. I guess my car is always outside, and either I just didn't notice it or simply wasn't loud enough. And, the search feature on the PDF manual works great!

Approximately five hours after the engine is turned off, you may hear sound
coming from under the vehicle for several minutes. This is the sound of a fuel
evaporation leakage check and, it does not indicate a malfunction.

 

@Vangm25 is absolutely correct. It’s an odd noise but totally normal.