I had my Prius for almost 4 years and I'm used to all the hybrid noises: brake pump after opening the door, emission control pump hours after driving, high pitched inverter noise in EV, etc. This is different. Very faint and I only noticed it because I opened the hood right after driving. The car was completely off, but there was some small electric motor activated somewhere inside the engine. Is this electric coolant pump? Edit: I recorded it on my phone, but the quality is not good enough to post. Barely noticeable over hissing.
I noticed a sound after I shut my car off it almost sounded like a ringing sound like I can get in my ears but it was coming from the car and I had my gf listen and she heard it to. I think it was pressure/ or coolant moving/ or anything...
Mine does this. It sounds like some sort of pressure bleeding off like coolant or refrigerant pressure. My car is nearly new and was recently serviced for the first time. I did not bother telling the service manager about it because I doubt seriously whatever is making the noise is going to cause a issue.
It's normal, but I'm uncertain which system is responsible. It is an electric motor. It has startled me several times when I've been servicing my Prius. Such as right after running the engine after an oil change to check oil level (once it has run for a minute or so). Shut the car off, go back under the hood to check, and it does this reported "whirring". Remember, there is a full two facing page notification in the GII manual that, once read fully amount to "any noise the car makes is normal".
