Two error messages persist after replacing toner cartridge.

Without removing the cover itself you really cannot be sure it is totally clear

after having opened the top and pulled it out. I recommend examining whether there is any evidence of loose toner in the machine at this point.Push the toner cartridge in to make sure it is properly seated.Then close the toner cover.Then close the scanner.

let me know whether this helps the problem any, or changes the machine's status.In Case You Still face Problem and Need Online Assistance Then Please Follow Us For On : Canon Printer Support

Error: "Invalid Toner Cartridge"; Error: "Invalid Refill"; Message: "Change Cartridge"
Solution
One of these error messages may appear on the printer display immediately after or shortly after a new toner cartridge is installed into the printer. Note: This may not be specifically a toner cartridge problem; the error may be due to a stuck cover open switch on the printer.

To see if the cover open switch is the cause of this problem, open the top front cover and observe the message on the printer's display panel. The display should read Close Door or Insert Cartridge.


If this message is not displayed, the top cover open sensor and switch will need to be replaced. In addition, the printer may have damaged the new toner cartridge. If the cover open sensor is not operating properly, a new cartridge can be incorrectly flagged as a refilled cartridge by the printer. If this happens, the new cartridge will continue to cause an Invalid Refill or Invalid Cartridge error even if you try reinstalling it or installing it into another printer. If this should occur, please contact the point of purchase of the cartridge to find out how to get the cartridge replaced.

Caution: If the cover open sensor is not operating, do not install another new toner cartridge until you have completed the directions below. Inserting another new cartridge can cause that cartridge to stop working as well. Should this situation arise, please take the following actions:


Place the original working cartridge (the empty or near-empty one) back into the printer. This should clear the error message.

Turn the printer off. Doing this will disengage the cover open sensor.

With the printer switched off, open the top lid and remove the old toner cartridge.

Now replace the old cartridge with another new Lexmark toner cartridge.

Power the printer back on. The printer should now read this cartridge as a newly installed toner cartridge and the error should be cleared. The printer and toner cartridge should function properly now, but the top cover sensor on the printer will still need to be replaced.

If your printer is still under warranty or covered under a service contract, please contact Lexmark Technical Support or your service provider for further recommendations and instructions. Until you can get the cover open switch replaced, remember to have the printer powered off whenever you replace the toner cartridge.

If the top cover switch appears to be working fine, or if you have followed the above steps and your printer continues to post an Invalid Toner Cartridge or Invalid Refill error, make sure you are using a new original Lexmark toner cartridge. A toner cartridge remanufactured or refilled by a third party can cause this error.

To help identify a refilled cartridge, look for the yellow label attached to the toner drum and the body of the toner cartridge. If this is damaged or removed, the cartridge may have been refilled.

If you are using a third-party refilled or remanufactured toner cartridge, it is recommended that you install a new Lexmark brand toner cartridge. Lexmark cannot guarantee the compatibility of any third-party toner cartridges with our printers.

OR

1 Switch on the Lexmark X83 printer.

2 Lift open the cartridge door at the front of the device, below the scanner unit. The printer automatically moves the cartridge carrier to the correct position.

3 Pull each ink cartridge toward you to unclasp it from the carrier. Lift the cartridge out of the cartridge carrier.

4 Clean the copper contacts on the bottom of each cartridge with a clean, dry lint-free cloth. Use a gentle, circular motion to clean the contacts.

5 Insert the ink cartridges back into the cartridge carrier. Push back firmly on each cartridge until it snaps into place.

6 Repeat each step in this procedure again. Close the cartridge door.

Sorry to hear you are having problems. Printers can be very frustrating at times. Below is a description of how to complete clear paper jams paper can get jammed it there pretty tightly and in very small places. Ensure you've followed all the steps to clear your paper jam and you should see your printer start working again. Refer to your user guide (or download via the link provided at the bottom) for illustrations.

1. Open the front of the printer.
   
2. Slowly take out the drum unit and toner cartridge assembly. Some of the jammed paper will be pulled out with the drum unit and toner cartridge assembly.
3. Set the drum unit and toner cartridge assembly on a piece of disposable paper or cloth in case you accidentally spill or scatter toner.
4. To prevent damage to the printer caused by static electricity, DO NOT touch the electrodes inside the printer.
5. Close the front cover.
   
   Note: Do not put the drum unit and toner cartridge assembly back in at this point.
   
   
6. Pull the paper tray completely out of the printer.
7. Pull the jammed paper down and out of the printer.
8. Open the back cover (back output tray).
9. Still looking at the back of the printer, pull the tab toward you to open the fuser cover.
10. Pull the jammed paper out of the fuser unit.
    
    HOT SURFACE
    After you have just used the printer, some internal parts of the printer will be extremely hot. Wait for the printer to cool down before you touch the internal parts of the printer.
    
    
11. Close the back cover (back output tray).
12. On the drum unit you set aside, push down the green lock lever and take the toner cartridge out of the drum unit. Clear the jammed paper if there is any inside the drum unit.
    
    
    CAUTION
    Handle the toner cartridge carefully. If toner scatters on your hands or clothes, wipe or wash it off with cold water at once.
    
    To avoid print quality problems, DO NOT touch the roller part of the toner. Try to keep you hands, fingers and everything else away from there.
    
    
13. Put the toner cartridge back into the drum unit until you hear it lock into place. If you put the cartridge in properly, the green lock lever will lift automatically.
14. Open the front cover. Put the drum unit and toner cartridge assembly back in the printer.
15. Put the paper tray firmly back in the printer.
16. Close the front cover.
17. Make sure that the Error LED is now off.
    

http://www.brother-usa.com/ModelDocuments/Consumer/Users%20Manual/UM_HL_2140_2170W_EN_1160.PDF

Sorry to hear you are having problems. Printers can be very frustrating at times. Below is a description of how to completely clear paper jams. Paper can get jammed in there pretty tightly and in very small places. Ensure you've followed all the steps to clear your paper jam and you should see your printer start working again. Refer to your user guide (or download via the link provided at the bottom) for illustrations.

1. Open the front of the printer.
   
2. Slowly take out the drum unit and toner cartridge assembly. Some of the jammed paper will be pulled out with the drum unit and toner cartridge assembly.
3. Set the drum unit and toner cartridge assembly on a piece of disposable paper or cloth in case you accidentally spill or scatter toner.
4. To prevent damage to the printer caused by static electricity, DO NOT touch the electrodes inside the printer.
5. Close the front cover.
   
   Note: Do not put the drum unit and toner cartridge assembly back in at this point.
   
   
6. Pull the paper tray completely out of the printer.
7. Pull the jammed paper down and out of the printer.
8. Open the back cover (back output tray).
9. Still looking at the back of the printer, pull the tab toward you to open the fuser cover.
10. Pull the jammed paper out of the fuser unit.
    
    HOT SURFACE
    After you have just used the printer, some internal parts of the printer will be extremely hot. Wait for the printer to cool down before you touch the internal parts of the printer.
    
    
11. Close the back cover (back output tray).
12. On the drum unit you set aside, push down the green lock lever and take the toner cartridge out of the drum unit. Clear the jammed paper if there is any inside the drum unit.
    
    
    CAUTION
    Handle the toner cartridge carefully. If toner scatters on your hands or clothes, wipe or wash it off with cold water at once.
    
    To avoid print quality problems, DO NOT touch the roller part of the toner. Try to keep you hands, fingers and everything else away from there.
    
    
13. Put the toner cartridge back into the drum unit until you hear it lock into place. If you put the cartridge in properly, the green lock lever will lift automatically.
14. Open the front cover. Put the drum unit and toner cartridge assembly back in the printer.
15. Put the paper tray firmly back in the printer.
16. Close the front cover.
17. Make sure that the Error LED is now off.
    

http://www.brother-usa.com/ModelDocuments/Consumer/Users%20Manual/UM_HL_2140_2170W_EN_1160.PDF

Change the toner cartridge , i have many units phaser3200 and this is one of the problem , but only if the toner cartridge is very old and many time refilled , if not , change the Laser unit .

1. Remove a misfed document if the copier displays a message reading "Document Jam." Lift up the document feeder cover and turn the roller to remove an Exit Misfed document. Lower the document feeder back into place and feed the document through again. If the document is jammed on the Input side, open the cover and gently pull the misfed document to the right and out of the feeder.
   
2. Pull out the paper tray and lift the tray to release it from the copier if the copier displays a message reading "Paper Jam O." Remove the jammed document, and open and close the side panel of the copier to clear the error message.
   
3. Unplug the power cord and plug it back in again if the copier displays a message reading "Fuser Error, Open Heat Error, Heating Error and Overheat." If the problem persists, call for a service.
   
4. Remove the toner cartridge and shake it from side to side if the copier displays a message reading "No Developer Cartridge." If this does not do the trick, you may need to replace the cartridge. Pull the release latch to open the side cover, and open the front cover. Twist the cartridge locking-lever upwards and remove the toner cartridge. Insert the new cartridge and lock the lever into place. Shut the front cover and the side cover.
   
5. Power off the unit and power it on again if the copier displays a message reading "LSU Error." A problem has occurred with the Laser Scanning Unit. If the problem persists, call for a service.
   

Clear the jammed paper as follows.
Observe Cautions signs in printer.
Always remove all paper from the paper tray and straighten the stack when you add new paper. This helps prevent multiple sheets of paper from feeding through the printer at one time and prevents paper jams.
1. Press the cover release button and then open the front cover.
2. Slowly take out the drum unit and toner cartridge assembly. The jammed paper will be pulled out with the drum unit and toner cartridge assembly.
3. Pull the paper tray completely out of the printer.
4. Close the front cover.
5. Pull the jammed paper up and out of the printer.
6. Open the front cover again.
7. Open the back cover.
8. Pull the tabs at the left and right hand sides toward you to open the fuser cover (1).
9. Using both hands, gently pull the jammed paper out of the fuser unit.
10. Close the back cover.
11. Pull the duplex tray completely out of the printer.
12. Pull the the jammed paper out of the printer or the duplex tray. Put the duplex tray back in the printer.
13. Push down the blue lock lever and take the toner cartridge out of the drum unit. Clear the jammed paper if there is any inside the drum unit.
14. Put the toner cartridge back into the drum unit until you hear it lock into place. If you put the cartridge in properly, the blue lock lever will lift automatically.
15. Put the drum unit and toner cartridge assembly back in the printer.
16. Put the paper tray firmly back in the printer.
17. Close the front cover.
18. Make sure that the Paper LED is now off and the printer is ready.
After clearing paper jam if noise persist printer may need a Repair Tech and parts replacement for broken or wore parts.

I had this problems and did everything suggested on here. Installed firmware update (which just changed the error message - didn't get rid of it), removed paper, changed size, replaced paper, tried new cartridge. Nothing worked. Finally found a tiny piece of paper that must have been blocking the sensor. It was on the left side near where the power cable is. It was less than an inch square. Got it out with some tweezers and problem solved.

I have a brother mfc 7840w

I first used the electrical tape trick and that worked for a while. Then got the toner low message again. I then tried the *00 trick, which works as follows:

1. lift lid and open front cover
2. press clear/back. "Replace Drum?" will appear on the screen.
3. Press "*00" it will then read accepted and the toner low error (End of Toner Life) should go away.
4. close it all up and your done.