I did some work on the engine, it's a BDV 2400 V6 175hp. There's a thin black plastic pipe, about 6-8mm diameter, running from a point low down in the front right of the engine bay to an assembly of switches and connectors mounted on a plate high at the back of the block. It's printed with >PH6H< and 21-06-02 FRJ, and thanks to my clumsiness is now in three pieces, I think it's become brittle with age so snapped easily. The car seems to run OK without it, but who knows what detail of engine management is now lacking. Predictably I suppose the local Audi dealer professes total ignorance and suggests I book it in for an inspection so that they can get paid to scratch their heads and wonder. Does anyone have any idea what this little pipe, be it vacuum or pressure, does and how I can replace it?

Hello Derek,

You may be lucky with someone coming up with an answer based on your description. 

OK, you may have previous poor assistance experiences at an Audi dealer, but surely this is where the answer lies via. the shortest possible route. 

If it were mine, I would be visiting my local dealer, armed with your salvaged bits and location description, and talking with the parts department who should be able to provide a schematic of what you need. 

Kind regards,

Gareth.