Help you out. hmmmmmmm

Stop Wasting your money trying to save the customer money by buying bodged up / repaired parts from anywhere.

Yes, I know we all do it and end up shooting ourselves in the foot.

It ends up costing you several hours of wasted labour and grief off the customer because his cars not fixed all because youve tried to get it repaired.

I would buy a New ecu from BMW or Bosch and at least you have a good idea that you are fitting something thats most likely to be fault free. ( Although even then, not always )
And the chance of getting the same fault on a New unit is very slim leaving you with a clear view of what the next step is if it doesn't cure it.

( and at the worst, you then end up with a new part on your shelf for the next one if it doesn't cure it )

P.S. When you have done all your tests, i,e continuity, short to earth etc and proved that your sensors are ok ( as you have ) then there should be little point sending anything away for testing. just stick your neck out, buy a replacement and keep your fingers crossed, i wouldn't trust any testing company to test a component on a bench as you can do better testing on the vehicle.

Although I see why youve had it tested etc as it gives you that feeling of being certain that your diagnosis was correct and you are not wasting any money buying something that you dont really need. ( if they do the job properly )

H.T.H. Tony.