Well, the crank position relearn on effects the crank position sensor. NOTHING else. I would need to read up on exactly what it does, but it seems to me the computer would send out its proper reference signal and adjust to what the sensor sends back.. To learn the sensors variation..

Seems like a way for gm to cheap out on manufacturing of sensors. (probably why when you buy a vw sensor its 2-3x the cost. but that cost is made up in paying for a relearn)..

I dont know what to tell you about the dealership. I hate hearing about the run around, unless you called at lunch time then i would expect them not to be there. But they should be there if you call back a little later. But if you knew your codes, i cant see a justifiable reason for the o2 unless you dont drive a lot and the o2 was still logged in the code history. Which in 3 weeks it shouldn't have been unless you haven't driven through enough cycles.

But ti comes down to them not fixing the light anyhow.