emissions valve, opens at cold start to allow secondary air pump to pump air into the exhaust to light the cats.Over time, I've come to know (by necessity) almost every large item in the M54 engine bay ... but some items still are unknown to me ...
What is this engine part?
intake DISA valve
heater valve for the dual HVAC system
VANOS solenoid/ VANOS adjustment unit
hose to CCV from valve cover
that is simply an electrical connector you have circled, unless my eyes are missing something
The "box" with all the brown wires is a common chassis ground for several things.
that would be the high side.