Direct tyre pressure monitoring fault

[GeraldGTE]

Hi all,
Hoping someone can help me out before I go thru the expense of a main dealer visit. I have a 2012 passat sport with the direct tyre pressure monitoring system. It has recently failed, no display on the MFD of pressures, and the flat tyre icon flashes yellow then stays a solid yellow. Now this didn't really bother me, but it appears this is an MOT failure and mine is due!! Local garage has dried connecting up the diagnostic but cannot find the monitoring system. They have on other passats.
Any ideas ? Is it a separate system with separate fuse ?? Any help or pointers greatly appreciated.