No release valve on the RS3 8P. Replace the sensor once the car has been sat for a day or two. Word of warning that sensor to do in situ is a right pain in the a**e!! I’d recommend removing the upper inlet manifold for access.
Myself and few others found out G247 could actually be down to a software update as Audi released a TPI for this parameter. It’ll be worth checking your engine software version. On the RS3 8P it should be 0060 whereas the TTRS 8J is 0050. It seems members with version 0030, 0040 & 0050 especially tuned were having issues with G247. I had this issue and spent about £3k replacing hardware to try to get to the bottom of it. It was only a software update required.