what is this?

sorry, need to know what the solenoid  is circled on top left? the little bottom hose has split.
thanks

It's the idle control valve, if the idle drops when you turn on the lights, blowers etc it will increase the idle speed.

Most of the time it's not used.

Have a look here for part numbers etc…

https://volkswagen.7zap.com/en/rdw/

many thanks , would the split hose cause any cold idling issues?🤔

Could do... try and wrap some electrical tape tight around it to stop any air leaks and see if that helps...

ok will do, hope it cures poor cold running and sputtering.