Help me name the part and it's function

[S4alan]

The thing is busted and hissing real loud and I have A CEL. Car seems to drive like normal. Am I harming anything by driving it?

General location pic



The thing in the center. It has alot of hoses connected to it.

[passatkid]

The round thing with a hose on each side is a Check valve in the vac system.

[mholme]

It is a check valve or one way valve. Shouldn't be that much from a worldpac or local dealer. But if it's for the car in your avatar...that's the least of your worries...

[S4alan]

Thanks guys! The car in my avatar died last year thanks to an uninsured driver hitting me at 50mph. I bought an avant to replace it.