Ip4500 keeps giving error message " ink tank error has occurred, open cover and replace ink tank where light is off" . Firstly, no light is off, only flashing at bk. we have tried 3 new cartridges (original) and still same error

Replace the applicable ink tank with a new
one, and close the scanning unit (printer
cover).
Printing with a once-empty ink tank can
damage the printer.
To continue printing without replacing the
ink tank(s), press the Resume/Cancel
button for 5 sec. or longer to disable the
function to detect the remaining ink
amount. After the operation, it is recorded
in the printer EEPROM that the function to
detect the remaining ink amount was
disabled.

As long as the ink is still in the original packaging, there is no expiration date.
I have (had) the same problem w/ my Canon PIXMA ip4200. Most annoying and then some! I finally cleaned the contact points on both ink cartridge and on printer w/ cotton swab lightly dipped in alcohol. Seems to be working now - time will tell for how long!

Canon Knowledge Base Replace the ink tank iP4500

• If it flashes orange five times consecutively, that means there is a print head error.
  
• Reseat the print head, then reset the printer.
  
• To reseat the print head, make sure the printer is on.
  
• Open the paper output tray and top cover.
  
• Make sure the print head holder is in the center and open the inner cover.
  
• Remove all the ink tanks.
• Raise the print head lock lever and remove the print head.
  
• Reseat the print head and lock the lever.
  
• Replace the ink tanks.

You have a bad cartridge.Take it back to the store where purchased or call Canon.

Normal 0 Driver could be corrupt.
Disconnect the printer or at least be sure it is turned off. I'd do both and reinstall the CD software program that came with the printer. When the software program asks you to connect the printer to the USB port, do so and it should again work properly.
Hope this helps. Bud

Reset Canon MP600 to the Factory Setting

1. Press the HOME button.
2. Use the Easy-Scroll Wheel or the right/left arrow to select Settings, and then press OK button.
3. Use the Easy-Scroll Wheel or the right/left arrow to select Device settings, then press the OK button.
4. Use the Easy-Scroll Wheel (B) or the up/down arrow to select Reset settings, then press the OK button.
5. Use the Easy-Scroll wheel or the up/down arrow to select Yes on the confirmation screen and then press OK.
6. Press the HOME button to return to the HOME menu.

ON THE CHIPS, TRY CLEANING THEM WITH ALCOHOL (70%)

SOME BRANDS YOU CAN SHAKE THE CARTRDGES TO RESET THE INK COUNTER

Call Canon, this is a chip error on the ink tank itself, they replaced mine.

Solution: Insert one of each color ink tank MP830

New Page 1 More Than One of the Same Ink Tank is Installed When installing or replacing an ink tank, only one of the following ink tanks should be installed. If the ink tank is not installed correctly, an error message will display.

1. Confirm that the printer is powered on and press the Open button. (The paper output tray will open.)
   
   
   
   
2. Lift the scanning unit (printer cover) completely. (The print head will move to the replacement position.)
   
   
   
   Note: When the scanning unit (printer cover) is opened more than ten minutes, the print head moves to the right side. If this occurs, close the scanning unit (printer cover), and open it again.
   
   
3. Open the inner cover.
   
   
4. Press on the tab to release the ink tank, then remove it from its slot. If you are replacing multiple ink tanks, make sure to replace one by one.
   
   
   
   
5. Insert the ink tanks into the print head. Note: Press the mark "PUSH" on the ink tank firmly until you hear a click.
   
   
   
   
6. Ensure that all the ink tanks are installed properly and the ink tank lamps light red.
   
   
   
   <7> The ink tanks are installed properly.
   
   <8> The ink tanks are not installed properly.
   
   Note: Ink Tank LampYou can check the status of each ink tank according to the way its lamp flashes.
   
   • - On: The printer is ready to print.
     
   • - Slow flashing (at about three second interval): Ink is low. Prepare a new ink tank.
     
   • - Fast flashing (at about one second interval): Ink tank is empty, or the printer is not ready due to an error.
     
   • - Off: An error has occurred and the printer is not ready to print.
     
     
7. Close the inner cover and the scanning unit (printer cover). Note:
   
   
   
   • When closing the scanning unit (printer cover), be careful not to jam your finger.
     
   • When starting printing next time, the print head cleaning launches automatically.

According to Canon's website:

Details Print Friendly Version Issue: ERROR LCD: More than one ink tank of the following color is installed U071
Solution: Replace defective ink tank (MP500 / MP800)

Replacing An Ink Tank Use the following procedure to replace empty ink tanks or when an ink tank error appears.

1. Confirm that the printer is powered on and press the <Open> button. (The paper output tray will open.).
   
   
   
   
2. Lift the scanning unit (printer cover) completely. (The print head will move to the replacement position.)
   
   
   
   Note: When the scanning unit (printer cover) is opened more than ten minutes, the print head moves to the right side. If this occurs, close the scanning unit (printer cover), and open it again.
   
   
3. Open the inner cover.
   
   
4. Press the ink tank's tab (1), then remove it from the slot (2).
   
   
   
   
5. Unpack the ink tank and pull the orange tape off completely in the direction of the arrow and remove the film.
   
   
   
   Note: Tear the orange tape carefully along the dotted line. If the orange tape remains, printing problems may occur.
   
   
   
   
   <4> Tape is completely removed.
   
   <5> Tape remains. Remove the orange protective cap located on the bottom of the ink tank by twisting as shown in the diagram.
   
   Caution: Do not touch the ink tank contact <6>. Doing so may cause printing problems. Do not squeeze the side of ink tanks as this may cause the ink to leak out. Do not reattach the protective cap once you have removed it.
   
   
6. Insert ink tanks into the print head.
   
   Note: Press the mark <PUSH> on the ink tank firmly until you hear a click.
   
   
   
   
   
7. Ensure that all the ink tanks are installed properly and the ink tank lamps light red.
   
   
   
   <7> The ink tanks are installed properly.
   
   <8> The ink tanks are not installed properly.
   
   
   Note: Click for Ink Tank Lamp indications.
   
   
8. Close the inner cover and the scanning unit (printer cover).
   
   Caution: When closing the scanning unit (printer cover), be careful not to jam fingers.
   
   Note: The next printing begins, the print head cleaning will begin automatically.
   
   

Ink Tank Lamp indications
You can check the status of each ink tank according to the way its lamp flashes.

• On: The printer is ready to print.
  
• Slow flashing (at about three second interval): Ink is low. Prepare a new ink tank.
  
• Fast flashing (at about one second interval): Ink tank is empty, or the printer is not ready due to an error.
  
• Off: An error has occurred and the printer is not ready to print.