I had this issue in mine which was (is) caused by corrosion on the toothed pickup wheels on the front wheel hubs. The sensors do not receive an accurate tooth count and think the wheels are slipping when they are not.
Since replacing the front wheel hubs is both expensive and a PITA and I don't care too much about ABS I just disabled the whole system. I unplugged the ABS computer under the dash, turning it off all the time and removed the ABS light from the cluster. If my currently perfectly good wheel bearings ever fail I'll re-enable it but I don't care for replacing the parts just for the sake of the toothed wheel.
It's almost impossible to clean the wheels since the only access to them is through the hole that appears when you remove the ABS sensor.
Just something to think about. Your sensors may be fine but what they're reading could be the problem.