Canon Color imageCLASS MF9170c Service Manual page 265

Chapter 14
Code
E020 Error in density sensor
0000 Description
Cannot receive enough light when detecting image density.
Cause
Dirt on density sensor, error in density sensor, error in DC controller PCB, error in
toner cartridge.
14-4
Description Action
- Replacement of ETB unit
- Error in high-voltage joint (Check high-voltage joint for each
color, and each joint to high-voltage PCB)
- Replacement of DC controller
- Replacement of toner cartridge