A thin white line, or several, runs from the top of the page to the bottom in the same place every time, cutting through text and filled areas. On a laser printer, that means something is stopping toner from reaching that strip of the page. Low or clumped toner, dust on the laser window or LED print head, debris on the drum or cartridge roller, and scraps in the paper path are the usual reasons. This guide moves from quick fixes to part replacement.
What you might be seeing
- One or more white lines run the full length of the page
- The lines stay in the same position on every print
- Filled areas and large text show the gaps most clearly
- Lines appear more often as the toner gets low
Common causes
- Low or uneven toner
- As the cartridge empties, toner can clump or run thin across part of the roller.
- Dust on the laser window or LED head
- A speck or paper fiber blocks the light along one narrow strip, so that area never attracts toner.
- Debris on the cartridge or drum
- A paper fiber or hardened lump of toner on the developer roller or drum stops toner in one line.
- Obstruction in the paper path
- A stuck label or paper scrap can scrape unfused toner off the page.
- Damaged drum
- A scratch or worn band on the drum can stop it holding toner along that line.
How to fix it, step by step
Work through these in order and test a print after each one. Most people are done within the first few steps.
With the printer off and unplugged, give the fuser about half an hour to cool before reaching inside. Wipe spilled toner with a dry cloth rather than a household vacuum.
Confirm the line stays in one place
Print two or three copies of a page with large dark areas. If the white line sits in exactly the same position on each, the cause is fixed inside the printer. Lines that wander or change point more toward the paper or the toner supply. Keep one page so you can compare it with later results.
Redistribute the toner
Open the front cover, take out the toner cartridge and hold it level. Tilt it gently from side to side five or six times to spread the toner along its full length, then reinstall it. If the lines fade or disappear, the toner was low or unevenly spread. Check the supplies page and order a replacement if the cartridge is nearly empty.
Clean the laser window or LED print head
Switch off, unplug and give the printer about 30 minutes to cool. Your manual explains how to reach the laser scanner window or LED print head. Some printers have a cleaning slider or tab you move back and forth; LED printers usually have LED bars under the top cover that you wipe gently with a soft, lint-free cloth. Use liquid only if the manual recommends it.
Check the drum for debris
Remove the drum unit or the all-in-one cartridge and set it on a sheet of paper, away from bright light. Look at the drum surface without touching it, since skin oil marks it permanently. If a speck or fiber lines up with the white line, remove it as your manual describes. Put the drum back within a few minutes, as prolonged light exposure can damage it.
Look for scraps in the paper path
With the printer still unplugged and cool, shine a flashlight into the paper path, rear door and duplex area for stuck labels, torn paper or staples. Anything rubbing against the page between the cartridge and the fuser can wipe off a stripe of loose toner. Remove it gently by hand, and never scrape at rollers with pointed or metal tools.
Try fresh laser paper
Paper dust, damp sheets and heavily textured stock can stop toner transferring in places. Load paper from a newly opened ream labeled for laser printers and print your test page again. If the streaks change or vanish, the old paper was part of the problem, so keep reams sealed and away from humidity.
Replace the cartridge or drum
If the line remains, fit a new toner cartridge first, since it's the part replaced most often. If the line is still there and your printer has a separate drum unit, check drum life on the supplies page and replace the drum. On printers where toner and drum form one cartridge, a single new cartridge replaces both.
How to keep it from happening again
- Replace toner when the printer reports it low, before streaks start
- Keep the printer covers closed and the area dust-free
- Use laser-rated paper and store it sealed
- Never feed label sheets with missing or peeling labels
Common questions
Why does rocking the toner cartridge help?
Toner is a fine powder that settles and clumps over time, especially as the cartridge empties. Tilting the cartridge gently spreads it evenly so the roller is coated across its full width. It's only a temporary fix for a low cartridge, but it confirms whether the toner supply caused the lines.
Are white lines and black lines caused by the same thing?
Not usually. White lines mean toner isn't reaching part of the page, so the light path, the toner supply or a blockage is to blame. Dark vertical lines usually come from a dirty charging part or a scratch that attracts extra toner. Some causes overlap, but the fixes differ.
Can I clean the drum with a cloth?
Most manuals advise against wiping the drum, because its coating scratches easily and absorbs skin oils. Some describe lifting off a loose speck with a dry cotton swab while rotating the drum by its gear. Follow your manual's method exactly; if the drum is scratched, replacing it is the only fix.
This guide is general information written for common home and office printers. Menus and button names vary between models, so check your printer’s manual where a step differs. Printer Problems Solved is independent and not affiliated with any printer manufacturer. See our disclaimer.