Just for your information, i had a Citroën Xantia, which develop a ABS warning light, I went to my local garage and asked them to check it for me. But how much would it cost?, the answer I was given at the time was £44.00 to put on the diagnostic machine, so i ask them to go ahead, that wasn't the end of it, they put it on there machine, but it was not given out any codes to tell them what was wrong. They told me that they had a young lady which had the same fault and they start to replace the sensors. So i asked them if i need to replace the sensors how much would this cost me, reply was that the front wheel sensors was £74.00 each and £28.00 for fitting, and the rear sensors was £79.00 each and £28.00 for fitting, if this dose not work then i would have to replace the ECU unit at a cost of £258.00, as you can see that the cost go's up and up this is not including VAT which is added at the end. My comment is find yourself a car mechanic and paid him and tip him and he would be a lot cheaper, make sure he will give you a guarantee.