What is that noise the Prius makes after it is shut down? I'm sure it is suppose to do what it is suppose to do, I'm just curious what the noise is. Thanks.
You are probably hearing the coolant heat recovery pump. It runs for several seconds upon cold engine startup and frequently also runs upon shutdown. The pump is moving coolant to and from the coolant heat recovery system canister, which stores ~3 liters of hot engine coolant. The idea is to speed up cold engine startup to reduce exhaust emissions during engine warmup.
