PANAsonic 6020 photocopy machine error E3-40 Density sensor problem resolve

SOURCE: How to clean Density Sensor of Hp 3500 ?

Thank you for this info. I used your advice to fix my HP printer and it worked. By the way, great link to HP support parges on the www.partshere.com site. I was able to fix my printer and by the way purchased more printer parts and fusers. Thank you again!

SOURCE: "981 Service Switch Error" and "994 Servise Density Sensor"

these are internal error. beyond user capability or repair
turn off the printer and check all of the cable connections.
turn on the printer, you need to call lexmark service, if the error returns.

SOURCE: exposure density sensor problem. how do l solve it?

If you remove your drum unit, you can see the sensor inside. Make sure it is clean. If the problem returns, check the toner support of the drum unit. It is probably dropping toner onto the sensor. You will also see flecks of toner on your copies if the toner support is bad.

SOURCE: How do I clear machine error code E04-01 on a

How do I clear machine error code E04-01 on a Panasonic DP-3030 photocopier?