Unknown Noise before engine on

[YourBlueHedgehog]

Hi.

I drive a 2016 Ford Focus and have come up with something weird.

As I open the door to get in the cabin there is a popping or knocking noise that seems to (I think) come from the roof - I can't quite tell.

The engine is off and I haven't put the key in yet.

What can this be?

Once I start the car it seems to go away but what can be making the car make noise when it's not on. It goes away when it's off, i don't understand.

Thnx for your help,

H.

I would expect to hear the fuel pump prime as the door is opened. Often sounds like a ticking or a hum and wouldn’t sound like it’s coming from the roof.

Thnx for getting back!

The temperature has varied and it seems pretty consistent. It's good you think it might be natural and ok that it goes away after a bit of running, it puts me at ease a bit but i can't help be freaked out a bit. I'd just assumed if something was to go wrong it would be when you turned it over, then you'd hear some knocking. It freaks me out a bit but I guess I'm just gonna have to live with it. Thnx for your advice.