CLK 230 Kompressor engine bay noise

[Cyprus]

Hi all
Posted a question a few weeks back on another subject, thanks for the replies.

Anyway...had the front right-hand indicator bulb blow today, replaced that and is working ok now. However, while I had my nose stuck inside the engine bay I noticed that the two components (arrowed yellow in pic) make a very audible humming/buzzing noise with the ignition switched on (position 2) but with the engine not running. Should they do this? Cannot say that I have ever noticed this before, never had the need to stick my head inside the engine bay with the ignition on and engine off before!! Or an I just being paranoid ....

Car is a '99 CLK 230 Kompressor.

Also, bit of a side question, are there any reputable independent Merc servicing people in Norfolk?

Cheers folks.

 

[Uncle Benz]

Both are electronic throttle modules. One is the throttle butterfly itself, the other is the supercharger bypass flap. Buzzing with ignition on and engine not running is normal and not a cause for concern.

 

[Cyprus]

Right-oh, thanks for the reply. Was just very curious because the noise is so noticeable!!

Cheers.