The error code C4200 means the laser scanner could be defective, or the polygon motor, or the mainboard.
- Switch off and unplug the printer for 20 minutes
- Plug back and switch on.
- Replace the scanner laser (LSU): 302C993092
- Replace the mainboard (302DA94020 or 302DA93030)
- Replace the motor board (302DB93011 or 302DB93010)