F 51 indicates lack of resistance around the motor. If you see this code, make sure there are no items stuck under the agitator or between the tubs. Do not overload your washer and use voltage specified by the manufacturer. Also, the rotor position sensor (RPS) may have failed and it is not reading properly any more. Check connectors at the RPS and clean it, if necessary. If they have rusted badly, they may need to be replaced. Restart the cycle. If the error persists, repair or replace the RPS.