Line down middle of scan

Check your flat bed and Document feeder scanning glass need to be clean, if any dot or dust in scanning glass of document feeder it will appear a line, check this points first
1- Check printouts from computer or FAX if it is clean problem in scanning section
2- Check using Copying a blank paper using only Flatbed if it prints without any line its problem from document feeder Scanning glass
So solution is clean the Document feeder scanning glass using wet cloth, note careful about wet cloth switch off the machine and clean it

Hi,
if you have already cleaned all the areas in scanner, then the reason should be an error in your scanner interface cable. This is the flat, grey cable which is connected to scanner lamp. Try to disconnect it and connect it again. When you use your Canon just for printing, there should be no dark lines.
Also maybe you scanner lamp has a problem. These things you can't repair.
Good luck
pifonski

please just you scan the object to resuleasion in and dp is 600 to 12oo select and you scane object and aply print is dark is ok.

Check for damage, residue, or excess toner on your imaging drum, transfer belt, or transfer roller.

You need to remove the toner cartridge if fitted pull out the toner holder, making sure the opening is on the top, if not the toner will spill out, set this to one side and clean the toner holder thoroughly.

first of all try to make a copy..when you make a copy if you get lines..then clean the scanner glass and the rollers..if its still the same..connect the printer directlu to the wall outlet and then check

It sounds like you have a dead spot in your imager. 

Try leaving the cover open and run a test scan, once with a fresh sheet as the item to be scanned and then a second time without anything on the table.  You may see what is blocking the light source or possibly a defect in it.
Scanning is done left-right, left-right across the width of the page and the vertical stripe indicates that the blockage is present during each scanned line.
In servicing copiers and multifunction machines, I have found a number of curious contaminents, one of the most annoying was a moth, still alive, that would randomly sit on the lamp, causing some pages to come out OK, others not. 
If your copies and printouts are coming out fine, then only the scanner can be at fault.

If you make a copy, does the copy have dark areas down the middle of the page? If so, remove the toner cartridge and gently roll it around to redistribute the toner inside, maybe even replace the toner cartridge if you've had it a long while. If you still see unevenness, you may need to have the machine looked at.

If the copies you make on your machine look fine, then I would suspect that the person sending you the fax has a dirty scanning element. Check with them to see if they can clean the scanning element and it should improve the fax quality.

Any difference between using the document feeder and just the flat bed?