So, what's this then?

[g-a-c]

I can't find an engine diagram on Google, and I'm not a full CS member yet so I dunno if there's one on here. Happened to notice this while I was checking the oil...no idea what it is, but my experience of finding/putting screws into engine hoses on my previous cars tells me that it didn't leave the factory like that! Car's running well (except the radio) so it's obviously nothing particularly important, but I'd still like to know.

 

[Ol’ Tarby]

It's had the acoustic valve removed and the vac pipe blocked up. A common mod and nothing to worry about

 

[BoatNonce]

Looks a bit screwed.

 

[g-a-c]

A common mod and nothing to worry about

I figured it'd be something like that, it's the same method (and probably the same size screw) I've always used to stop troublesome EGR valves from operating on my VAG TDIs. Couldn't see it being anything important as the engine runs perfectly well

 

[MarcB]

As said above regarding the valve being removed.

I bought some red silicone hose long enough to hide the screwed end away into the chassis leg where the valve should be if ever it needed replaced

 

[g-a-c]

I'm not too worried, the bay is far from pristine and I don't have the valve anyway. If the valve is supposed to be in the arch, I guess mine's been chopped short then to make it easier to block up (and more importantly, easier to see if it becomes unblocked)?

 

[Addicted]

Yep in the arch, many take them out.