Reset the printer by turning it off, then turn it back on.
if this doesn't solve the problem theres probably a paper jam, even a very small part of paper can cause the jam or it can be caused by pretty much anything thats not supposed to get inside the printer.
here are my instructions for clearing paper jams:
- Turn off the printer.
- Remove any paper trays. Inspect them for wrinkled or damaged paper.
- Also open the back cover of the printer if this model has one.
- Open any other doors that give access to the printer's paper path and to the toner or ink cartridge.
- If necessary, remove the toner or ink cartridge. Place it away from light/ sun light to avoid damaging it.
- If you find a piece of jammed paper, remove it byholding it with both hands and pulling firmly. The goal is to keep thepaper from tearing. If several pieces are jammed together, try pullingout the middle piece first to loosen the jam.
- If the paper does tear, try rotating the roller gears manually to free the paper. Don't force anything, though. Dothis step especially if the jam message comes up repeatedly without anyobvious paper jam, there may be a small tear of paper inside.
- Ones the printer is free of paper Replace the toner orink cartridge and paper trays, close any doors you opened and turn theprinter back on.
- If the printer paper jam message still appears, then there is still some paper in the printer. Reinspect the paper path.
- see alternative if the problem is still not solved.
Loada piece of thick paper, for example photo paper and press the resumebutton (may be diffrent button on diffrent models) a few times to theprinter picks up the paper and puts it through the machine.
Here is what canon suggest:
Remove the paper following the procedure below. (1)
Slowly pull the paper out, either from the Rear Tray or from the Paper Output Slot, whichever is easier.
If the paper tears and a piece remainsinside the machine, turn the machine off, open the Scanning Unit(Printer Cover) and remove it.
Be careful not to touch the components inside the machine.
After removing all paper, close the Scanning Unit (Printer Cover), and turn it back on.
If you cannot pull the paper out, turn the machine off and turn it back on. The paper will be ejected automatically. (2)
Reload the paper in the machine, and press the OK button on the machine.
If you turned off the machine in step (1), all print jobs in queue are canceled. Reprint if necessary
Also, have a look at what other people have said/ done with the same problem:http://www.fixya.com/support/t159885-error_code_6000