Buzzing noise

Went out into my garage last night to clean off the sides of my car cause I got bored and I immediately heard a strange buzzing noise. I thought it was coming from outside, but I soon realized it was coming from under my car towards the rear end. I bent down and looked underneath to try and see where it was coming from but couldn't really tell. It went on for about a minute then eventually just died out. It definitely sounded mechanical. I had turned off my car like 5 hours before that, so it wasn't the turbo cooling down or anything like that. Any thoughts? kinda scared me.

the fuel pump normally makes a slight buzzing sound on startup..could be that.

My car wasn't running, so unfortunately it rules out the fuelpump. And it was definitely coming from the back of the car.

The ECU is testing the evaporative emissions system for leaks.
What you are hearing is a pump (near the fuel tank).

matsuda said:

The ECU is testing the evaporative emissions system for leaks.
What you are hearing is a pump (near the fuel tank).

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Wow....well thanks for the info. how often does that happen? first time I've noticed it.