hi ive got a 03 st170 my abs and traction light was on after loads of checking i found when the new disks were fitted they didnt clip the sensor wire back onto the shocker and it rubbed on the inside of the wheel and split the sensor wire i removed it and solderd it back together cleared the codes and abs and traction light are off and there both working fine now . might be worth removeing the wheel on the side it was changed and checking the sensor just incase hope this helps cheers mark