Loose plugs at back of engine bay?

[Bingbloke]

Hi
My mate has just bought a A4 avant b7 sline TDi.
Unfortunately a whole host of issues to sort and working our way through them.

odd question...

engine has gearbox at the back towards the bulk head.
there are two loose cables/connectors???
One orange and one black.
Neither plugged into anything?
Any ideas what they are??
Thanks

 

[Bingbloke]

These are the plugs

 

[tr7]

Possibly the O2 sensor I think? Plugs into connector on the firewall/bulkhead

 

[NHN]

Orange one has snapped of its home so to speak as its got part of the female end still attached & other either unplugged or come off.