https://redirect.viglink.com/?format=go&jsonp=vglnk_159315271418712&key=91dd979d1264adf2b3d1ec7bb9c85926&libId=kbvtylji01001qxx000MA429ivo5o&loc=https%3A%2F%2Fwww.ttforum.co.uk%2Fforum%2Fviewtopic.php%3Ff%3D2%26t%3D307325&v=1&opt=true&out=http%3A%2F%2Fwiki.ross-tech.com%2Fwiki%2Findex.php%2F17925%2FP1517&ref=https%3A%2F%2Fwww.google.co.uk%2F&title=The Audi TT Forum • View topic - Part number for ECU RELAY J271 %3F&txt=http%3A%2F%2Fwiki.ross-tech.com%2Fwiki%2Findex.php%2F17925%2FP1517
if it's the relay, (not loose/corroded connections to Fuse 10) then it's undert he bonnet (see link) remove it and it will prob have a part no stamped on it.
http://forums.audiworld.com/showthread.php?t=1893163