2004 Toyota Prius Make a Weird Noise

Reader Question My 2004 Toyota Prius makes a loud screaming noise from the engine compartment after shut off for 5-30 seconds (about 50-70% of the time) and sometimes after starting for 5-10 seconds (about 3% of the time).

Only one of the 3 service managers has heard this, he has a 2007 and it makes the same noise. I am going to try to claim this as something the mfg should fix since it is “technology in the works” kind of like beta computer programs.

That one service manager says it is probably either the inverter or something else on which he can’t be specific. He says the inverter is covered for 80,000 miles, and I was happy to see anything at all other than the big $3000.00 battery (100,000 miles) was still covered.

He says that if the noise is fixed, it might not be permanently fixed because hybrids have so many on and off again peculiarities, he agrees with me that sometimes you have to press start 2 times or shut off 2 times just to make it work, he says peculiarities are common on hybrids.

If somebody at corporate says this might not fix the problem, and it is not the inverter, that would make it harder for me to convince the mfg to pay all of the cost or a portion of the cost. If it is the inverter the image of peculiarities might make it hard for me to convince them to even replace the inverter.

Peace, Progress, Blessings to you


Hey there Rodger

I am still LEARNING all I can about the Prius, and unfortunately don’t have an answer for you….or even a guess as to what to do. If you don’t mind updating me on what you find out with this problem I am certain it will help out the next person.

Austin Davis

Hi Austin

You asked to hear what it was, it was a heater water pump ( bearing) . As soon as they replaced it, I was about to leave the dealer and I wanted to test the car, so I did, and it was making a whirring noise from what was probably the same area roughly, about 1-5% as loud as the worst times before it was fixed, they pulled a new Prius next to mine to show me the new Prius made the same noise.

I said well, it never made that new noise ever before and so I wanted them to keep it another day. They did at no charge but they charged me that extra day for their rental car and said it is just typical of hybrids, that they make noises, they did not have an answer as to why it never made the “new sound” after they fixed it.

I have a friend with a Prius with 110, 000 miles and he never had any such trouble and it was a BIG NEW ISSUE with all 3 service managers and the two service writers I dealt with.

Tell me anything you think I should know about Prius hybrids………………………… mine now is at 57000 miles.

Have a good Spring season.

Wish me good luck………………..good luck to you.

Peace and Progress


Hello again Rodger,

Thanks so much for your time to keep me posted. I will post this on my site and HOPEFULLY we will get some feed back from other readers about their experience since I am still “green” when it comes to the Prius. I will keep you posted when I hear anything.

Thanks again!


Austin Davis

Posted in: Noises

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