I have a big black line down the middle of my scans

If that is the last page that has the streak use a blank page in the original scan as the last page and then the dark line wont cover the image.

I suspect the Document Feeder is not aligned properly and light is leaking in. You will need to have a technician in to check the alignment of the scanner to see if it needs to be readjusted. random black lines on edges usually indicate light leaking into the scan area.

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

Check the scanner glass for ink or lint residue. This is what normally causes lines on faxed and scanned documents and pictures. Here is a link to explains it and shows where to check for the residue.

http://www.ccl-la.com/blog/index.php/lines-on-scanned-or-copies-pages/

There are two possible fixes.

Download the latest firmware update by CLICKING HERE

The following is provided by courtesy of Lexmark:
Problem Vertical lines; Auto document feeder scan anomaly; ADF scanning problem; Scan issue; Scanner issue; Visible line; Streaks show on page; solid line down the page; Top to bottom line; Smudge runs down the page; Opaque line; Broken line; Bar all the way down the page Solution Overview

This article provides the self-diagnostic steps necessary to evaluate top-to-bottom streaks that appear when copying or scanning.

Important! This is seldom a scanner hardware failure.

The main reason for this anomaly is debris or marks on the scanner glass that is used for Auto document feeder (ADF) page scans.

Printed or Scanned Page Illustration

Who should consider this article?

Any user of an MFP or All-In-One printer experiencing the following symptoms:

• -Vertical lines only when using the Autodocument Feeder (ADF).
• -Observed with any type of scan job (e-mail, ftp, solutions, fax).
• -However, normal expected output when the page is scanned from the scanner flatbed.

ADF scan behavior

Think of it this way:

• -The page is pulled from the ADF.
• -The moving page slides across an ADF-designated portion of glass.
• -The image sensor, which is located under the glass, reads and interprets the moving page's contents.
• -Contamination on this ADF glass is seen by the image sensor for the entire length of the page.
• -The image processor interprets the image sensor's repeated capture of this contamination as a vertical solid line.
• -Any ADF scan function now exhibits a vertical line.

Suggested Diagnosis and Fix

Step Action 1 Locate the portion of the glass designated for ADF scans.
HINT: The glass location differs by model. This area is often separate from the scanner flatbed. Please reference User's Guide for more information if you are having a difficult time locating this designated area.
2 Perform a visual inspection for any of the following recurring culprits:

• -Clear adhesive tape
• -Glue
• -Ink pen
• -Paper
• -Marker
• -White out
• -Staples
• -Environmental dust or dirt

HINT: Ink marks can be especially hard to see and almost translucent at first sight. However, the image sensor (CCD) registers them as a mark. 3 Use a clean, soft, moistened cloth to thoroughly clean and remove any marks or debris. 4 Inspect the underbelly or underside of the ADF for any marks or debris. 5 Perform another scan to see if cleaning the glass alleviated the issue. 6 Repeat the procedure if a vertical line still appears.
Remember! Printing and scanning from the scanner flatbed work fine.
7 This time, place an intentional mark on a blank sheet of paper and take note of its location. Now place that sheet of paper in the ADF and make a copy.
8 Evaluate the distance of the vertical line to the your mark. 9 Inspect that area of the glass for further debris or marks and clean as necessary.

Other Possibilities


If... Then... Vertical lines appear only when printing... Consider other printer-related topics such as toner cartridge, charge roll, photoconductor, transfer roll, or fuser. Contact Lexmark Technical Support. Vertical lines appear when you lay the page on the flatbed... Consider other printer-related topics such as toner cartridge, charge roll, photoconductor, transfer roll, or fuser. Contact Lexmark Technical Support. Vertical lines appear on ADF-fed printed copies, but they do not appear on scan-to-network [e-mail, FTP, folder (PC), solutions]... Consider other printer-related topics such as toner cartridge, charge roll, photoconductor, transfer roll, or fuser. Contact Lexmark Technical Support.

It could be due to some dirt on the scan lens on the printer. Refer to this article on How to Clean the Scan Lens and White Roller on the Lexmark X4250/ X4270/ F4270. I hope this helps.
If you need additional assistance. please contact Lexmark technical support so they can help you. thanks.

If line is vertical.

Try scanning a bigger document. Use a blank page big as the scan capacity and scan the blank page.

If for example you are using an a3 scanner, scan a blank A3 page.

When scanning blank page set resolution to an high value, so that you does not lose pixels.

Check scan result, and explore the whole document using zoom to see if the line is still present on the test scan of the blank page.

If there is still the line, then it is either a scanner dirty, probably inside glass, or a dafective sensor on CCD sensor array.

If there is no line, then the problem is usually depending on the software.

In that case uninstall the software and install it again.

If that is not enough to fix the problem, try uninstalling software, doing a system restore to a date before the problem started , and then installing software again.

If the line is horizontal , that is usually a loss of power on the high voltage to lamp.
Try reinstalling software first, if that does not fix the problem , and line is horizontal, then it is fault mentioned above.
Horizontal lines at the end of a document may also be caused by faulty scanner control board, or scanner going out of memory.

The correct answer is to clean or replace the mylar sheet on the bottom of the adf

lift the auto feeder and clean the scanner glass that your pages scan across -it is dirty. You can make a copy afterward and this will tell you if you have solved the problem.

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.