How to remove E error on Canon P20-DX adding machine?

Overflow Interlock Function, fix ??? you may be at the end of life on calculator. you can buy another on eBay.

Do you mean the "E" for Error
OR
E For Exponential

1.Remove the battery, lens and CF card. Allow the camera to sit without power for 20 minutes and then reinsert a fully charged battery.
2.Turn the camera on and push the shutter button as if you were taking a picture.
3. If you don't get the error message reattach the lens and insert the CF card.
4. Check the below canon eos 350d service manual link:
http://goo.gl/ELh523

it will help you to save a lot of money
Hope it helps, Thanks

http://www.canon.es/Support/Consumer_Products/products/Fax__Multifunctionals/InkJet/PIXMA_MP_series/PIXMA_MP495.aspx?faqtcmuri=tcm:86-774538&page=1&type=faq

Follow these instructions.

See these instructions.

HI, What is p20 in canon mp495

Canon Pixma Mp258 Error Code and Possible Solution

P02 (Carriage error)
1.Make sure no foreign material stuck to the print head railway.
2.Clean and check the print head encoder strip cable (timing **** film or encoder strip is a white line on the back of the box set of ink lines may be missing or mess up the ink.P03 (Line feed error): an error in transmission line entering the line feed (LF) is a signal telling the printer to move to another line or a whole new line that would not otherwise have reached the end of the line.
1.Check wire print head position (timing **** disk film) on the side of the machine.
2.Check PCB logic board.
P05 (ASF sensor error) sensor for paper feed error.
1.Try to replace the following:
•ASF / PE sensor unit.
•Drive unit.
•PCB logic board.
P06 (Internal temperature error): caused by abnormal heat inside the printer.
P07 (Ink absorber full): the Ink Wastepad (sponge) inside the printer is full
1.Replace the wastepad inside the printer or install waste ink bin outside the printer
2.then Reset counter protection.
P08 (Print head temperature rise error): caused by thermal print head temperature exceeds a threshold.
1.Replace the new cartridge print head and / or change a new logic board.
P09 (EEPROM error): caused by corrupted or defective EEPROM chips of the printer.
1.Replace the logic board.
P15 (USB VBUS over current): caused by too much current, try removing the USB cable and then plugin again, if solve the error, try to replace with a new USB cable. If the error still exist replace the logic board.
P20 (Other hardware error): The failure of other hardware.
1.Try to replace the logic board.
P22 (Scanner error): a scanner malfunction.
1.try to change the scanner unit or change a the logic board.
E13 or E16: Ink has run out

1.Pressing the Stop / Reset button for 5 to 8 seconds until the led screen display number 1.
E04, E05, E14 or E15: Cartridge may not be installed properly
1.Reinstall the ink cartridge.

Set the answering machine to answer on 4 rings and the fax to answer on 6 rings.Do this with answering machine menu.

It's difficult to see, but the feeder for the paper is on the back of the machine, just below where the roll of paper goes. You'll see a little slot above the opening for the batteries. Feed the paper in here and push the arrow up button above the ON/C button to get the paper feeding through the mechanism. It should pop out at the top!