I have a sharp ar-m257 has a service code H4-20. What does that mean

Maybe order the service manual
http://www.servicemanuals.net/ServiceManual/SHARP/ARM237/572062/detail.aspx

This is a low fuser temperature error.
You should be able to reset it by doing the following at the panel.

Hit Pound, star, C, Star
enter 14, then touch start
execute on the screen
the machine will reboot and the code should go away.

if the problem persists you may need some maintenance.
If you're in Houston we'd be happy to help you out.
Skelton Business Equipment Houston Copiers

Hit Pound, star, C, Star
enter 14, then touch start
execute on the screen
the machine will reboot and the code should go away.

If it persists you may need some maintenance. If you're in Houston give us a shout. Our labor rates are low compared to the other Sharp dealers in Houston.

Skelton Business Equipment Houston Copier

Please log in machine with you browser with machine ip address
and user name and password is admin and Sharp and go to address book and remove anything you do not want.

Your fuser is not warming up. Try clearing with Sim code 14. If the problem comes back, one of your 2 fuser lamps is broken or your thermistor is covered with toner.

Hi,

The default username/password is
admin ( all lower case)
Sharp ( capitol S, the rest lower case).
Hope this helps.

open frount cover remove toner cartridge. remove blue screw be carefull dont damage drum.developer unit out ,clean old developer and apply new developer .then re install all of them and input code 25-2 and let the copier to run and stop automaticly.

There are a few thing's > have you cleaned the optic's > clean the primary charge unit in the drum unit > how old is the drum & developer? Also, is the copier calling for for "Maint's Req"

Got a service manual and looked up the parts ;)

L1-00 is determined as "scanner feed trouble". The scanner unit (which holds the mirrors) is not moving as it should be. There are a few possibilities. Firstly, does the mirror unit move when the copier is turned on? if not it could be a disconnected/broken scanner wire or bad drive motor or simply dirt/debris or a loose wire binding the unit up.
If the unit moves on power up then it could be a bad sensor or a bad board not registering the signal from the sensor.
You can check the operation of these items in SIM mode : press the following keys one after the other "P" "*" "C" "*" then press 1 and enter/copy button and you'll see the option available.
I hope that helps.