Use VAGCOM (which you can either buy or use a freeware copy from RossTech) or a VAG fault code reader. I use the freeware VAGCOM installed on a laptop with a cable from ebay that plugs into your OBDII port (under the ashtray).

Have a search and ye shall find.
 
vagcom leads are only a tenner

mind i cant get mine to work :lol:
just goes not responding but i think it may be vista, shame i have nowt else to try