Hi guy's, I have a problem with my A4. The ABS light comes on intermittently. I know there is an actual problem as my front right (o/s/f) locks up under heavy braking. I did buy a new sensor assuming it was that corner that was the problem and fitted it but it hasn't gone away. The other wheels seem to 'work' OK. It varies day to day, when or how much it comes on. But generally it's on all the time I noticed while changing the front there was mud and **** on the ABS ring (which I cleaned)... But surely if it was that, it would come on all the time, yes?