When i braught the car 8 months ago it had a abs problem whch turned out to be a fualty sensor at the drivers side front, changed this for a new one from vw and problem solved....then two months ago the abs light started comin on and going off so plugged in my hand held obd2 scanner and it told me that the offside rear was fualty.
Got my mechanic to change this for one from kms but the light would still come on for a while then turn off then on again. mechanic striiped it all down and checked the ring and rotor plus that there was no play in bearing, told me the new sensor must be fualty and that if i got another he would replace this while i wait for free...hasnt been done yet as im busy....
Last week though the abs light came on and didnt go out on the way back from london, so today i plugged the scanner back in and it now had two fualts, the one at the rear and now the one i replaced eight months ago at the front

any ideas? help