Hi
This might be some help?
Code Function Check Points
E4- 01 Fuser warm-up temperature 1. Fuser Thermistor is dirty.
2. Thermistor position is incorrect.
3. Fuser temperature is low. (Adjust F6-31)
4. Thermistor is defective.
5. Fuser Lamp connector is disconnected.
6. Fuser Thermostat is defective.
7. Fuser Lamp is defective.
8. HTC PCB connector (CN716) is disconnected.
Gordie