One of the codes that came up at the BMW dealer when it was brought in with the failed engine was the DME: Valvetronic, eccentric shaft sensor2: guide and reference.
I did some digging and discovered that the valvetronic sensors have a tendancy to malfunction. These sensors and motors control the valve system in the car, allowing the valve system to open up and let the car rev. I discovered that if this valve system were to malfunction it could throw off the engine timings and potentially cause serious mechanic damage to the engine internals.
Another code, that came up while driving away from the dealer was the limp home activation. I believe this is the code that the tech cleared without checking. Limp-home could be activated by a number of other serious issues, such as valve problems.
A code that came up when the car was brought in for the wiring harness AND when the car returned with the failed engine was the DME: differential-pressure sensor, intake manifold: plausibility.
I found out that this sensor figures out what the pressure is in the manifold and tells the valvetronic system to open up and relieve pressure. I also found that if this sensor malfunctions serious damage to the engine can occur if it isn't fixed. This sensor would also cause limp-home to be activated. I discovered on another forum that the valvetronic system can be locked down by the pressure sensor if it is malfunctioning. This pressure would then build up as the car warms up and would cause the engine to fail.
This seems to be pretty clear information that if BMW had been diagnosing my vehicle correctly that they might have been able to save my engine.
