2000 S40 ABS Brake faults - reoccurring after ABS sensor repair

[tsteenka]

I've seen a number of threads regarding the failures of Bosch ABS sensors on this model. This S40 has 150k and had the classic symptoms, ABS, Brake lights on, speedometer not working. Researched a few of the repair sites for the Bosch unit and went with BBA Reman as it is closer to my location.
Reinstalled unit, it worked for about 20 minutes and then same symptoms reappeared. Intermittently it would decide to work again, usually on the first start of the day. Sent it back to them for verification, which they subsequently claimed passed all their tests. Reinstalled unit and again it worked initially only to fail within the first day. Very frustrating. Unable to communicate with unit for diagnostics. What am i missing?