The sensor. If it's the oil pump, err either or both of the oil pumps, then the LH cover comes off, the clutch basket etc...not too bad really (at least you don't have to split the cases), and that would be a good time for a barnett clutch upgrade. That's right two oil pumps. But it sounds like the sensor is bad. If you order a sensor, also order at least one each of the RH & the LH cover's gaskets. These are really a must to have if you ever have to get behind the covers and hold any hope of riding the same day.
