Fitted new n/s/r abs sensor today. Sourced part from bavariandominator.co.uk. Looks the same as the BMW part, fits perfectly and works as well!!! Not a bad result for £20. In the end I bought both an INPA cable and a C110 reader. They weren't a lot of money and both work fine. The C110 is just a quick and very easy to use tool which I now carry in the boot (just in case). Thanks for all the advice.