I replaced both ink cartridges for the printer, won' print.

clean the heads and d/l print utilities

Most likely, it is a print head issue. The print head is what the printer cartridge sit in inside the printer. To fix the problem, please do the following:

1) Open the printer and wait for the carriage to slide over.
2) Remove the ink cartridges from the print head.
3) Use cotton swabs dipped in hot water or a mix of hot water and isopropyl alcohol to clean the printer head and electronic contacts on ink cartridge.
4) Repeat the same procedure until no ink residue coming off on the cotton swab.
5. Once finished, allow to dry and put back the ink cartridges in.
6. Try printing.

If the above troubleshooting won't work then maybe one of the cartridges is defective or both. If none of the cartridges are defective, then you need to replace the print head.

I hope this helps.

carlo

The error code indicated, the print head is defective, so it will not get solve by replacing any number of cartridges. Just follow the steps below to reseat the print head, if that does not help, then replace the print head.

1. Confirm that the printer is powered on and press the <Open> button. (The paper output tray will open.)
   
   
   
   *MP800R shown
   
   
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. Remove the ink tanks by pressing the tab of each tank.
   
   
   Caution: Handle the ink tanks with care so that your clothes and surrounding area do not get soiled. Make sure to remove the ink tanks one by one.
   
   
   
   
5. Raise the print head lock lever.
   
   
6. Tilt the print head slightly towards the front of the machine and lift out gently.
   
   
   
   Caution: Do not touch the print head nozzles <1> , electrical contacts <2>, or ink supply ports <3>. Doing so may cause printing problems.
   
   
   
   
7. Place the print head in the print head holder and lower the print head lock lever carefully until you hear a click.
   
   
8. Insert ink tanks into the print head.
   
   
   
   
9. Press the mark <PUSH> on the ink tank firmly until you hear a click.
   
   
   
   
10. 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.
    
    
11. 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.

Most likely this is a print head issue. The print head is what the cartridges sit in inside of the printer. To attempt to resolve it, do the following:

(1) Open the printer
(2) Remove the ink cartridges from the print head.
(3) Use cotton swabs dipped in hot water to thoroughly clean the print head and each ink cartridge.
(4) Repeat this until there is no ink residue coming off on the cotton swab.
(5) Once finished, allow to dry and replace the cartridges
(6) Try to print something now

If that does not work then you have one of two possibilities:
(1) One of the ink cartridges is defective and causing the error
(2) If it's definitely not that, then the print head will need to be replaced.

Printing with an empty ink cartridge may cause printer malfunction. U051 / U052
U053 / U059 The ink cartridge may not be set properly, or an ink cartridge not supported by the printer is installed.
Install the proper ink cartridge.
If one of the ink cartridges is missing, this error will occur. U075 / U076 The ink cartridges are not installed in the proper position. Install each ink cartridge in the proper position. U140 An ink cartridge not supported by the printer is installed.
Install the proper ink cartridge. U161 / U162 A used ink cartridge may be installed, or the ink cartridge may be empty.
Replace the ink cartridge.
By pressing the OK button, printing can be done without replacing the ink cartridge. However, the remaining ink amount cannot be detected properly, so the function to detect the remaining ink amount does not operate. READ/WRITE MODE Since the memory card is currently write-enabled, printing is not possible.
Set READ-ONLY MODE ON. NO PHOTOS ON CARD Some images in the memory card may not be in a supported format. images listed below cannot be printed directly from a memory card. Print them from a computer.
The waste ink absorber is a part inside the printer, which absorbs ink used in the cleaning operations, etc. CHECK PRINTER Turn the printer off, and remove the power plug from the outlet.
About ten minutes later, plug it in again, and turn the printer on.
If the problem is not resolved, the printer may require servicing. Please contact your local Service Center.

Printing with an empty ink cartridge may cause printer malfunction. U051 / U052
U053 / U059 The ink cartridge may not be set properly, or an ink cartridge not supported by the printer is installed.
Install the proper ink cartridge.

Make sure to install both the ink cartridges even when you set the printer to use only one ink cartridge (Color or Photo) in printing.
If one of the ink cartridges is missing, this error will occur. U075 / U076 The ink cartridges are not installed in the proper position.
Install each ink cartridge in the proper position. U140 An ink cartridge not supported by the printer is installed.
Install the proper ink cartridge. U161 / U162 A used ink cartridge may be installed, or the ink cartridge may be empty.
Replace the ink cartridge.

By pressing the OK button, printing can be done without replacing the ink cartridge. However, the remaining ink amount cannot be detected properly, so the function to detect the remaining ink amount does not operate. READ/WRITE MODE Since the memory card is currently write-enabled, printing is not possible.
Set READ-ONLY MODE ON. NO PHOTOS ON CARD Some images in the memory card may not be in a supported format. images listed below cannot be printed directly from a memory card. Print them from a computer.

- images edited on the computer
- images in a format other than JPEG or TIFF
- images with double-byte characters used in the file name
- images saved in a folder nested 4 or more layers deep INCOMPATIBLE CAMERA The printer cannot communicate with the connected camera.
Disconnect the cable between the printer and the camera to clear the error.
Confirm the following items and print again.

1. Confirm that the camera you are using supports PictBridge or Canon Bubble Jet Direct.
If the camera does not support either one, the printer cannot print directly from the camera.
2. Set the camera in PictBridge print mode before it is connected to the machine. This is required before printing for some cameras that support PictBridge.
Please refer to the camera instructions for more information about procedures required before and after connection to the printer.
3. There may have been no response from the camera for the prescribed time.
Re-connect the cable between the camera and the printer. WASTE INK NEAR FULL The waste ink absorber is getting full.
Press the OK button to clear the error.
Printing can be done until the waste ink absorber becomes full. If the waste ink absorber becomes full, please contact your local Service Center for replacement of the absorber and printer maintenance.

The waste ink absorber is a part inside the printer, which absorbs ink used in the cleaning operations, etc. CHECK PRINTER Turn the printer off, and remove the power plug from the outlet.
About ten minutes later, plug it in again, and turn the printer on.
If the problem is not resolved, the printer may require servicing. Please contact your local Service Center. HEAD ALIGNMENT ERROR Automatic print head alignment failed.
Press the OK button to release the error.
Check the followings and do automatic print head alignment again.

- Check if A4/Letter-sized paper is loaded in the auto sheet feeder.
- Check if the paper output slot is not exposed to a strong light source
- Print the nozzle check pattern to check the status of the print head.

If the problem continues, do manual print head alignment. LOAD PAPER If paper is not set, set paper and press the OK button. When paper is set, check each item and do printing again.

1. Confirm that unusable paper is not set.
2. Confirm that paper is set properly.
3. Confirm that recommended paper is used, and the number of sheets set in the auto sheet feeder is within the limit.
4. Cleaning the paper feed roller may resolve the error.

If the problem persists, the printer may require servicing. Please contact your local Service Center. PAPER JAMMED Remove the jammed paper.
If paper jam frequently occurs, check the following:

1. Confirm that no foreign material is inside the printer.
2. Confirm that unusable paper is not set.
3. Confirm that paper is set properly.
4. Confirm that recommended paper is used, and the number of sheets set in the auto sheet feeder is within the limit.

If the problem persists, the printer may require servicing. Please contact your local Service Center.

According to your owner manual from Canon, it says...

Ink has run out.
Replace the ink cartridge and close the Scanning Unit (Printer Cover).
If printing is in progress and you want to continue printing, press the Stop/Reset button for at least 5 seconds with the ink cartridge installed. Then printing can continue under the ink out condition.
The function for detecting the remaining ink level will be disabled.
Replace the empty ink cartridge immediately after the printing. The resulting print quality is not satisfactory, if printing is continued under the ink out condition.

Try the following the intensive cleaning info in this rescue kit to regain print quality. There is also a known issue with some CX machines where a pipe gets blocked and the ink in the head can't flow. This is covered in this other rescue kit info.

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.