A loose wheel bearing or improper adjustment will cause this . Also you can check the sensors by tracing the wire from the wheel upwards to the inner fender and disconnect it there then hook a volt meter to the connection from the sensor ,then spin the tire as fast as you can it should give you a voltage reading of a couple of volts. No voltage then sensor is Kaput . The rear one is a little harder to do and I have only had one go bad in my time. Make certain that there are no pieces or filings attached to the sensors by removing them and wiping them off.