NO SPARK

This is speculation, but I believe the ECU system designers did not want a running engine to stop at a critical time as you were driving so they allowed the car to run in "limp along mode" using previous data as long as at least one of the camshaft sensors was indicating a running engine even if the crank sensor had gone bad. However, once you turn off the engine it won't start again if the crankshaft position sensor is not good. I know the guy who designed a part of the ECU in Japan but he doesn't know if my speculation is correct.