Another weird mystery. Last night I returned to my car parked outside and there was a low to medium sound of an electric motor running from somewhere near the back bumper (car was shut off, not running). Car had sat for five hours on a slight incline, the outside temp was in the upper 40's at the time, and I had a quarter tank of gas in it. Turned on the engine, drove it home, parked in garage, shut it down, and no sound coming from the rear at that point. Never heard this before.
Only out of ordinary thing was I had taken it to the dealer earlier that afternoon for my 10k service. While there, they test drove it with their diagnostics attached (don't know where they attach that) to check on an engine vibration sound I've been getting while driving up hills (all checked out fine, they couldn't find anything). Don't know if their diagnostic check had anything to do with it, but I doubt it. Also, they had fiddled with the headlights while they had it, taking it off the auto mode and also pushing the stalk forward for the highbeams. Again, I doubt any of that was related, but just listing out anything out of the ordinary at the time.
Anyone have any idea what could have caused this motor sound coming from the rear bumper area? The only thing I could think of is the fuel pump, but I've never heard of any fuel pump making a constant noise for minutes long while the car is shut off.

 

lexus charcoal evap release gas fumes. Nothing to worry about. It sounds like motor running after 5min to 10min then it stop, don't worry just egnore the sound

 

Thank you, that makes a lot of sense. What I'm surprised is I've never heard this ever before on all the Lexus's I've owned. Also, the car had been sitting over five hours.... when or why would it decide to start the EVAP thing at that time? Tried doing some googling, but not much is coming up as to when and how long it runs.

 

I caught my car doing this just the other day. I think I had driven it in the morning, and it was early afternoon when I went to the garage for some reason.

 

A bit startling, to hear something running when you walk out to a car that's turned off. I don't mind now that I know, but to be fully honest, I am shocked and surprised I have never heard of this process until now. I don't know how that happened, after 30 years on car boards! lol

 

The sound you heard near the back bumper could potentially be related to the fuel pump. It's unusual for it to run continuously when the car is turned off, but it's not impossible.

 

Yes, I first heard it with my 2017 IS and now I heard it with my 2023 IS. In the garage. I would go into the garage at night to visit the recycling bin and hear a whirring sound. As usual, when it seems that the car is doing something strange, it is actually doing something smart. Today, I started to get out of the car and an audible alert sounded. Oh, it was the “check rear seat” alert as I had some items on the rear seat.