I wanted to share this with fellow diy'ers as I found limited info to help fix my ford focus 2004 1.8 tdci ABS system, While changing the clutch on my focus I was unable to part the n/side abs sensor plug under the wheel-arch so I ended up giving it a pull & ripped the plug apart, because of the damage to the plug I also thought I’d better get a new abs wheel sensor for the nearside as this would solve the ripped plug issue, after telephoning around I got a new one from GFS auto parts for £43, after re-building the car & fitting the new sensor I started the car & the clutch worked fine but the abs light wouldn’t go out , I have bought a fault code reader & the fault it showed was n/side front circuit failure which would not clear even though I had just fitted the new abs sensor, At the time I was not aware that the front sensors are interchangeable & had no issues before I started the work on the system so I thought I must have damaged the wiring loom plug end, I got a new set of wires & plug from the scrap yard from a another focus diesel & graphed them into the wiring loom, after checking again with my code reader still the abs lights stayed on, at this point I needed to get the car MOT’ed so thought it better to let my local FORD stealer put it on their diagnostic tool & help clear the fault & MOT the car, FORD told me that they couldn’t clear the fault from the ABS module & that they were getting little info back from the nearside sensor, I explained that it was a new sensor bought from GFS , FORD at this point asked me if I had fitted a new wheel bearing, I told them no , it was the original wheel bearing, FORD also mentioned that they had checked the wiring out that I had graphed into the plug & that it seemed to be ok, then they told me I must have shorted the wiring out when I ripped the plug apart & that the abs module was damaged & they wanted £1500 to fit a new one, as you imagine the car isn’t worth that now & I was pretty !Removed! that I had damaged this & had to take their word for it, Something didn’t seem correct & I had no way of challenging this! FORD has all the information & tools for the system after all! So I took my car home after parting with £150 for fault finding I removed the abs module, I found a company online called ECU testing & called them to arrange sending my abs module to them to check to find what was damaged & replace the parts & then send it back to me as they had what seemed a good turn around service of a few days & they could do this for about £200, they phoned me to explain that they had checked my abs unit & the fault was not in the abs module & that they had no problems clearing the codes from the unit, they sent the unit back to me for £75 & before it arrived I got on the phone to FORD explaining that I was not happy with what they had said & that they need to train their staff better to use the equipment that they use, I refitted the abs module to my car & turned the key & got the same problem code up again, at this point now I was starting to get doubts about who was correct so I looked on eBay & found another abs module for £40, when it came I fitted it to the car & turned the key & got exactly the same fault code, at this point I found out from looking on eBay for a new front abs sensor that they were interchangeable & I could have got one for about £15, I took the new nearside sensor off the car & put my meter on it, got 22.5m ohms & then got the driver’s side off & got 17.5 m ohm’s , this was where I noticed something different between the two front sensors, the new sensor when I tested it by reversing the polarity on my meter gave me an intermittent reading on the ohm’s scale, on the original sensor when I reversed the polarity to get a reading I got nothing, I realised at this point that there must be a diode in the original sensor & that the sensor I bought from GFS must be an incorrect sensor for my car, At this point I decided to go to FORD & buy a new sensor for £97, put it on the car & hey presto the abs light went out & the fault code cleared with my code reader, Only by finding out on the internet that the sensors are interchangeable enabled me to realise both front sensors should have been 17.5 m ohm’s because that was the reading I got from the new sensor I bought from FORD, How the hell did BUSSEY’s not spot this? These guys are meant to be the experts? As for GFS, well I believe they gave me what they thought was correct but it caused me a !Removed! nightmare all because FORD withhold information about the system, Also ECU testing proved to be correct as the fault was not with the old unit so full credit to them, Not impressed with BUSSEY’s think they need better training as they would have quite happily charged me £1500 for work that never needed doing! moan over & as I stated i've only posted this so it might help others struggling with the abs system.