How to Solve Error P,7 P7 or P07 (5B00) on Canon printers

Solution 1: If the device is not functioning properly or to clear memory, resetit.

• On the operator panel, press the button. (The display will go blank.) Note: It may be necessary to unplug the power cord if pressing the ON button does not shut off the printer.
• Wait approximately ten seconds and then press the button again.
• Wait until the device has completed its cycling process before submitting another job request. Note: It may be necessary to unplug the power cord and retry if the above steps do not clear the error.

Solution 2: 

Step 1: Entering Service Mode

• While the printer is OFF, press and hold the Start/Stop button (Resume/Cancel in some other models).
• While holding the Start/Stop button, press and hold the POWER button.
• When the POWER LED (green light) lit, release the Start/Stop button (still holding the POWER button).
• Press the Start/Stop button TWICE (still holding the POWER button)
• Release the POWER button.
• Wait for the LCD to display “0″ (zero).

Step 2: Using Resetter / Software

• Download Ressetter: http://www.ziddu.com/download/10241255/ServiceTool_1050.zip.html
• Run “service_tool 1050.exe”.
• Confirm detected USB-port numbers on USB port column.
• Click “Main button” on Clear ink counter section. Make sure there are papers in the paper feed because the printer will print after the process is complete.
• Click “platen button” on the “Clear ink counter” section. The printer will print again.
• Turn off the printer and then turn the printer on. You printer is ready for use.