The canon cartridges are now built with a chip that determines whether the tank is full or empty. So, once the tank is empty, it will still show "Empty" after refilling it. This can be avoided following some methods (which varies according to the printer). I found the following methods in a website (I don't remember the address; It was copied in my hard drive) to avoid "Empty" notice after refilling the cartridge. Mine is Canon 1800 and the second method worked for me. For canon 1800 follow the second method.
First method:
Applicable to following Models-
BJC series: bjc3000,bjc8200,etc
S series: s400,s600,s800,s520,s6300,s9000 etc
i Series: i255,i320,i350,i355,i450,i470d,i550,i560,i850,i950,i6100,
i6500,i9100,etc
Pixma series: ip1000,ip1200,ip1300,ip1500,ip1600,ip1700,ip2000,ip2200,
ip3000,ip4000,etc
Action-
Press RESUME/CANCEL button once.
Second method-
Applicable to following Models:
Pixma series: ip1880,1980,3300,3500,4200,4500,5200,6700d,pro9000,9500,ix4000,5000,etc
Action-
Hold down RESUME/CANCEL button for 5 seconds or more
Third method:
Applicable to following Models-
Pixma MP series: MP150,MP160,MP170,MP180,MP450,MP460,MP475,etc
Action-
Press START button once(COLOR button for colour cartridge and BLACK button for black cartridge)
Fourth method:
Applicable to following models-
Pixma MP/MX series: MP145,MP228,MP245,MP520,MP800,MX850,MP970,MX308,MX318,MX7600,etc
Action-
Hold down STOP/RESET button for 5 seconds or more
