you need to get the car diags read off and cleared.
when reading the codes it should give a speed error and which wheel is playing up.
(when mine failed it said the car was doing 655mph on one wheel whilst stationary
new cables are about £40 each new, sh 5-10 or so.
the fault can be cleared but the ABS system will not be operational untill all sensors are working correctly.
so find which sensor is playing up, though you could pull off each wheel in turn and remove/refit the sensor, they should be a very tight fit.
i would also check the barrel connector on the other end, some wd40 in there wont go amiss to keep any damp from causing contact problems.
the ones on the front are hidden up behind the splash guards in the arches.
do the refit/clean before you take the car back for diags read/clear/reset.