If the Defender's wheel hub is the same like the D2's it might not show any symptom from outside cos it can be an internal wear and the ring to have a certain play then the sensor's signal becomes unstabile but if there is movement in the wheel grabbed at 3 - 9 and/or 6 - 12 o'clock corroborated with wheel speed sensor fault code then the hub should be replaced. nanocom makes a stationary voltage test on the sensors to check the circuit and if it gets back voltages between 2 - 2.4 V it means that the circuits and the sensors are ok so if the fault comes while driving it's most probably what was explained above
