Oil squirting but where from

Hi all

I have a mysterious oil leak on my 2004 A4 1.8T. I removed the top engine cover and noticed that there was some wet oil on the pipework to the right. On further investigation , it looks like oil is squirting from somewhere but I can't see where from. There are squirt marks on the radiator expansion tanks as well as on the underside of the bonnet. 

I have run the engine in the drive with the cover off and can't see any sign of a leak even when revving the engine. 

Only other thing to add is that the engine warning light (amber) came on the other day so wonder if this is related? Not sure what the error is - assume I need to get a garage to scan the computer?

Anyone any ideas?

Thanks in advance

Lee.