C5 1.9 Tdi Loose part after EGR Valve

[alanjf]

I was carrying out a service on my recently purchased A6 1.9Tdi and noticed an oil leak. It meant the EGR valve and surrounding areas are covered in oil and general mess. I decided to clean up as I could then spot the issue in the future. Looking at the pipe after the EGR valve, I thought it could be coming from there. I loosened it off and while doing so a metal ring came out with it about 30mm long and diameter of 45 mm. You should be able to see it in the photo. I cannot see how it sits on the EGR valve and certainly not on the pipe as it is too wide. It was loose as I removed the pipe after the EGR valve. Any advice appreciated as I am reluctant to put it all back together without the part in place. Thanks Alan