buzz/hum when car is off and unplugged

I have heard the same thing. I just thought it was the car conditioning the battery. Just my guess!

 

although i have not heard it, could it be the cooling fan?

 

I don't think so it has a sound with kind of a low continuous click click click real fast. I have heard it maybe 3-4 times seems to only last a few minutes 1-2.

 

is it after driving? how long after?

 

I don't remember exactly but a number of hours 3-5 maybe? maybe even longer.

 

It's just the normal sound made by every Prius after they're turned off. No cause for alarm. I think it's the battery and engine 'readjusting' themselves. I'm certain the engineers on board can give a more precise explanation. But the main idea here is it's nothing to worry about.

 

Oh! I was not worried about it, I just chimed in to let them know someone else has heard the noise. I never heard it on my 2005 that I had for 7 years! It was just a completely different sound than I have ever heard. A real fast Purrrrrrrrrr noise almost like it was quickly checking every 57 cell to make sure they were ready to charge or something. It was not a fan noise. I'm not worried car is running great and getting about 16-18 miles of electric every day.

 

The noise that you are hearing is caused by the Evaporative Emissions System. It is the noise of the system running a test to check for possible leaks. It is always done several hours after the car is turned off. The sound comes from the fuel tank area.

 

Thanks for the explanation. I heard it once when the garage was cool, the car had not been run or charged in several hours, etc. I was waiting to catch it again and see if I could come up with a good description, as has been done here, before posting a question.

 

Thanks for the answer, Evaporative Emissions System check, would have never thought that might be answer!

Thanks again!

 

Phausto, Good call on the car being a sentient being I think your right, it's made the step!

 

You can also hear the noise if you have not driven the car in awhile, and then open the driver's door.

 

isn't that one under the hood?

 

The noise linked to the driver's door is from the Brake Accumulator pump. This assembly is located right underneath the driver side wiper area. This noise can also be heard while the car is on.