Hey guys,

I own a 94 C280
Shortly after starting and while running there is a loud intermittent buzzing noise coming from the boot of my Mercedes.

It sounds like
*Bzzzzzt* pause *Bzzzzzt* pause *Bzzzzzt*

After stripping back the lining I found a unit connected to vacuum lines.
Its the Black Box under the Spring in the following picture with the Bright Yellow vacuum line coming out of it on the right...




What Exactly is this unit?
Is it failing or is this due to a vacuum leak?

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Living sideways