My Copen also failed it's MOT on the wheel bearing. I had a new one put in as it was making a grinding noise. BUT the new one has now started making the same grinding noise and my ABS light came on. I collared my mechanic about it and he say the sesor was knackered as he had to take it out of the hub to get the bearing out. Anyway I've ended up ordering a second hand hub with bearing and sensor in it as Daihatsu want £180 for the sensor alone!! But why would my wheel start grinding again and they fail it on the bearing when its a brand new one!!