This message appears and printer is stopped when the PF motor is determined to be out of tune because the encoder pulse signal of specified range has not been input within required time during PF motor rotation or because the pulse is extremely long or because it is short.
Check Points:
No dirt or foreign objects on PF encoder or Scale,PF.
No abnormality with PF timing belt and proper tension of the belt.
No unusual loads on grid roller rotation.
PF motor resistance measurement.
Perform encoder check with self-diagnostic program.
Harness connections are correct and no shorts or wire disruptions.