On S5, the appropriate wire to cut is the 1C wire if you are trying to mitigate against the infamous flooding hot start issue according to several different posts. If I have read the posts correctly, the correct wire to cut on my S5 is the second wire from the right, top row, on the right most connector of three into the ECU. This is a black wire with a red stripe. I just need to confirm that this is correct for an S5 as the wiring is so much different at the ECU.

 

If you're looking for 1C it is indeed located on the top row second from the right. And you could remove the pin/wire w/o having to cut it. On the reverse side of the plug from where the wire is there is a clip inside the plug which needs to be pressed down on with a very small item and at the same time pull on the wire from the opposite side and it will pop out. Got this from HAILERS.

 

I answered this yesterday and downloaded a pretty little picture showing the wire for a series five.

 

Hailers is the man. The site was down yesterday evening and the server did not send me the response until today. That diagram is exactly what I needed!