High Pitch Whirring Sound

That sound is produced by the engine coolant heat recovery system pump, which operates upon start up and shut down. It is normal for the pump to operate at those times.

 

This is the sound of the pump returning hot coolant to the thermos tank. Some pumps get noisy in the cold but it does not affect the performance. If it fails a DTC code and warning light will appear. The car can still be safely be driven in this condition.

John (Britprius)

 

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turbo?

 

Hi Patrick,
I have a 2008 model, in Australia, and this car does not have a thermos. However- I get this whirring sound also. Sometimes I go into the garage and if I open a door, it may start. I wondered if it might have something to do with the key in my pocket, but this is not a smart key. What do you think this noise is? Is it something to do with brake line pressure?
Thanks,
David

 

Hi David,

You are hearing the brake actuator motor running. If the driver's door is opened while the car is IG-OFF, the body ECU communicates this info to the skid control ECU which powers up the brake actuator to build up pressure in the hydraulic system, thus getting the car ready to be driven.

Another possible noise that you may hear the Prius make after it has been parked for a few hours is that the fuel tank will be pressurized to check for leaks. You may hear a pump running for a brief interval when this test is executing.

 

Again Patrick the Australian Prius does not have a pump to pressurize it to check for leaks. It is only the North American continent Prius that uses the bladder system with the leak detection.

John (Britprius)

 

Ah- thanks Patrick. You're a gem!

Thanks John for the clarification. Aren't we lucky here down under

 

You get the same deal as us in the UK/EU.

John (Britprius)