2004 Audi A3 ASR

Hi,

I've an Audi A3 and the ASR light is intermittently coming on and staying on. The problem is getting worse as it is reoccuring more often and I reckon soon it will just stay on continiously. I’ve been told that this is related to the speed sensors located in the front and they might just need a clean to rectify this problem. I’ve tried to find out how to remove / replace these but haven’t gotten any good explanation. Do you think this is the best route and if so where would I find such info. If not what would you suggest

Thanks

Eoghan