I am getting e020 error switch main off and on again and again

Other possible causes:

https://printcopy.info/?l=en&mod=erc&brand=Canon&model=imageCLASS%20MF8080Cw&code=E020-0000

needs fuser assembly. probably bad thermistor.

Hello,
The probable causes for error :

The developer has deteriorated.
• The developing cylinder fails to
rotate.
• The developing assembly is not
locked.
• The toner concentration (patch
detection) sensor is faulty.
• The developer inside the
developing assembly is faulty.
• The toner level sensor is faulty.
• The concentration sensor is
subjected to stray light (no cover,
front cover open).
• The photosensitive drum has
deteriorated.

In error code E020-0481, means that the problem is in black developer. So I would first try to replace Bk developer, check the developer station for malfunctions ( broken gears, broken developing roller bushings,... ).

Hope that helps!

Check for blockage in toner supply ,located at rear of hopper. Also is the toner ok

Error :
Intermittent E020 / E061 codes.

Workaround :
It's possible that there is a poor drum ground from the static eliminator brush. You may need to replace the static brush with the drum grounding leaf spring from a CLC 350 (part numberFA5-9308-000). Follow the procedure in technical publication CTP.NO 700/800-69.
Error :
E020 sub code 0440 and light density on all colors

Workaround :
Check the developer assembly movement, i.e. up & down and that the magnetic roller is turning. Check the EPC readings, laser output, fold back mirror, and the connectors for the developer and the developer bias contacts. If all the above checks are good, then the problem can be with the AC voltage output of the developer bias HVT. The DC-voltage for the developer bias is split between two colors ( magenta & yellow ) or ( cyan & black ). The AC voltage is supplied for all four colors and it's loss will be seen in all the colors whereas the loss of the DC voltage would affect only two colors. To fix the problem replace the developer bias HVT part # FG5-3068-060.

ATR Error (E020-XXXX) Display due to Dirt on ATR Sensor Window


Cause
The waste toner may adhere on the ATR sensor window or the sensor shutter. As a result of that, it may be faultily detected as ATR sensor fault and trigger the ATR sensor error (E020-XXXX).


The detail codes (xxxx) are as follow: XXA0, XXA2, XXA8, XXA9, XXC0, XX10, XX11, XXDA.

Filed Measure
Clean the ATR sensor window and the ATR sensor shutter with the following procedure. 1) Remove the ATR sensor from the main body. 2) Press the plunger [1] of the ATR sensor lever solenoid in the direction of the arrow. 3) Clean the ATR sensor window [2] and the ATR sensor shutter [3] with lint-free paper [4].
Pls rate thanks!!!!!!!!! dont forget testimonial mate.

go on line type in

canon printer error e020 and look at all the ideas to help you fix your problems

rod

E020 try by push reset button until show $ upper left
then press key *4* and you will in service mode.
find code error 1 in LCD then press *
copier will restart.

change all your developers

SPECIFICALLY...you need to replace the Black drum unit.
the sequence of that particular error code is;
E020-01XX(Yellow drum)
E020-02XX(Magenta drum)
E020-03XX(cyan drum)
E020-04XX(Black drum)