2.2 sri part identification please

[no2lurch]

on my 2.2 sri, i need to know what a part is and if its supposed to be doing what it is! (camera broke but here goes)

its on the left hand side of the engine bay as you look from the front, behind the headlight - it has a electrical plug and what looks like a vacuum pipe. what is it?

mine clicks quite loudly - is this normal?

[mjb]

Is it round, brown, attached to the ECU box and has 2 pipe connectors? If so, it's the fuel tank pressure release valve which opens periodically while driving, and after you kill the engine, in order to let air into the fuel tank to stop a vacuum forming, which would prevent fuel flow