Hi I’m looking at extending the fuel line, and replacing it for new but unsure as to the diameter needed, it’s an eberspcher D2 unit and plumbed directly into my T5 fuel tank.

Which generation D2 Airtronic? The Eberspacher earlier generation D2 Airtronic heater requires a larger diameter black fuel pipe ( part number 09031125)  between the fuel source and the fuel pump - the fuel pipe between the fuel pump and heater then reduces to 1.5mm white opaque pipe part number 09031118

Hope trhat helps, remeber that the fuel hose connector pieces and hose clips will also be differen diameter.

Perhaps best confirm which generation Airtronic you have? and also which length of pipe you require?

Thanks for your enquiry