2001 X5 ABS failure(s)

[wmubrown]

Another source of contention... earlier this year, the ABS failure light came on and I lost my speedo. Thanks to this forum and X5world, comments led me to replacing the rear left ABS sensor. Problem solved... ABS lights went off, speedo returned to normal... but a week later, the ABS failure light came back on but the speedo continued to work. I got out the multimeter and found the rear right ABS sensor was now bad. I replaced it and the ABS remained off for about a day. Now the ABS failure light comes on randomly - whether stopped, or driving, come on, goes off, frequently and randomly. At $100 a pop per sensor, is there some way to figure out which sensor is causing the fault? Being intermittent, using the multimeter isn't going to be much help in diagnosing this IMO. Thoughts? Maybe the second sensor I installed is faulty? TIA.

John