The ABS / Traction control light won't go out on my W reg Fiesta Zetec S. Took it to my local garage on Saturday who have told me it needs 2 new front ABS sensors at £110 each

Have checked the sensors today and can't see an obvious damage to them and have also check the connecting plugs to make sure they are not corroded but all looks good.

Seems odd to me that both sensors would go at the same time, has anyone else had this problem or know of any other common faults which could cause the ABS light to come on?