Hello Everyone

I'am new to the forum and having just bought an A8 3.0 Tdi on a 2004 plate look forward to sharing info on the cars
First problem i removed the plastic cover on the passengers side under the bonnet above the bulk head to remove the leaves that had built up under there and noticed a wire with what looks like a black sensor with white small holes / rings,now when i start the car up the engine management light is on ? i don't have a clue where it has come from or where it belongs,obviously from the area under the plastic cover as the wire is not very long

Secondly when driving every now and then the glow plug light comes on and flashes and goes into a limp mode,turn the ignition off and re start the car and it will run fine,until it happens again,i have had it to a specialist who said there was a fault code something to do with pressure,but he just cleared the memory but problem has come back

I have the car booked in at Audi on Monday but would like an idea of what it could be,the engine management light i have just caused that this evening i think

Any help or info would be greatfully appreciated

Thanks Andy