Description: Paper tray empty or not seated correctly. A buildup of toner on the edges of the tray which slide into the printer can sometimes cause problems. Take a sharp tool, like a razor blade and scrape the buildup off these edges.
Defective Tray Size Sensing or Configuration - Most trays have tabs which depress a series of switches when installed. Verify that the tabs aren't damaged and that the tray switches located in the printer are not damaged. You can depress these by hand and hear them click. Occasionally the contact for the micro switch will get bent and will have to be replaced. Also verify the configuration through the menus on the printer.
Defective Paper Control Sensor PCB - These do fail and will need to be replaced.
Code: 12
Display: 12 Printer Open
Description: Paper top cover open.The top cover open or a broken tab on the cover assembly. On rare occasions a defective paper control assembly or actuator can cause this problem. Verify the tab on the cover is not broken.
Code: 13
Display: 13 Paper Jam
Description: Check the paper, make sure it meets the paper specifications for your printer. Tractor feed paper with the edges ripped off doesn't seem to work very well. Extremely heavy or thick paper is also a problem. Check the HP paper specification guide for more info. Be careful with labels, use only labels designed to take the heat generated by the fuser assembly. Regular labels my "ooze" adhesive as they pass through the fuser assembly and literally gum up the works! Also check for any partially peeled labels, this can be a disaster if they come off inside the printer.
Check the paper path for toner or paper dust buildup. Look for bits of paper lodged in the path particularly around the sensors.
Is the paper size correct? Is the software set for the size you're using? Is the menu set for the size you're using? Check these items. If the software tells the printer to expect a different size (legal, A4, COM10) than the tray available, you will get an error. This can happen when printing a FAX document formatted for A4 size paper.
You could also have a defective or dirty exit sensor. Replace or clean as needed.
Code: 14
Display: 14 No EP Cartridge
Description: No toner cartridge or cartridge not fully seated - pull it out and install it again.
Make sure at least one of the two drum sensitivity tabs are present. These are small rectangular blocks of plastic which contact the switches in the printer.
Can also be caused by a defective DC controller. Pretty rare though.
Code: 16
Display: 16 Toner Low
Description: Toner cartridge is empty or toner in cartridge is not distributed evenly. Gently shake the toner cartridge both from side to side and from front to back. This can generally get you 100 or so more pages.
Check the door open sensor flag, PS1. Also check the toner level sensor and the toner cartridge itself for damage. It can also be caused by a defective DC controller. You can verify this by substituting a known good DC controller if possible
Code: 18
Display: 18 MIO Not Ready
Description: The printer is not connected to a LAN when it's expecting to see a LAN. Terminate the port on the printer with a BNC T and two 50 ohm termination's.
The MIO card is defective or maybe just not seated correctly. Remove the card and reseat it, try swapping with a know good card from another printer. Replace if necessary.