After replacing a couple of minor items they came to the conclusion that an internal ground was the issue in the ECU (sorry, not cpu). Two days later the light came back on. I don't know why they can't seem to nail it down. Isn't that the whole idea with OBD? It seems like a guessing game. This is the fourth time to no avail. With 33K on the odometer, I sure hope they'll cover this issue should it go past the warranty.