My HP laserjet 3015 says ''check cartridge'' and ''check paper tray''. The cartridge it's new, an it has paper in the tray. What's the problem ?

Print a couple of pages. As the printer is printing open the toner cover. Pull the toner cartridge out and look down at the paper. If the printing looks good the fuser probably needs replacing. Before doing that, have you checked the toner cartridge.

is the toner cartridge original or reffiled.
Try with original one.
check if the image you print is correct printed on drum
to do this print something and when the printer start to pull the paper stop the printer by open a door. then pull out the toner cartridge and look the drum if the image seems ok If you see bad image you have problem with laser scanner or charge of drum.

PLS CHECK THE CARTRIDGE HI VOLTAGE CONNECTIVITY

Plz see if the corner of the paper will be folded or it has been folded earlier and now it is straight then also that paper will be jammed. So use new unfoiled paper.
While inserting it see it is straight in the tray.

Put paper in the manual feed tray(tray 1). Print something. When the paper gets about 1/2 way into the printer, open the top cover. Pull out the toner. Look down at the paper in the printer. Do you see a thick dark line? Replace the toner. No thick dark line, check the fuser for damage.

try pushing the paper a bit.

may be the paper are not in the right position.

or last ur sensor has some fault but i think it is just the paper are not in the right position, flaten the papers and slide them back in to the tray, and push the papers in a bit

good day

Follow these steps:

1. Remove all paper from the input tray.
2. Open and close the door.
3. Reinsert the paper into the input tray.
4. Powercycle (turn off and back on) the printer.

have you received any information?

Machine may be in econo mode. To enable/disable.
Hope this helps

1. open the Printer Properties (or Printing Preferences in Windows 2000 and Windows XP).
2. On the Paper/Quality tab or the Finishing tab deselect EconoMode check box.

Try going into the Maintnence Center, should be in Options or Maintanence and running it.