Use the direction, colour, and spacing of each line to isolate the cause before cleaning or replacing anything.
| What the page shows | Most useful first hypothesis | Next check |
|---|---|---|
| Horizontal white gaps in one or more colors | Inkjet nozzle or ink-flow problem | Print a nozzle check and identify the affected color. Run nozzle check |
| Horizontal bands only in photos or gradients | Draft setting, alignment, or bidirectional pass issue | Use normal quality, then check alignment and feed accuracy. Run alignment test |
| Vertical line in the same place on every page | Paper-path contamination, toner, or imaging drum | Print a laser density page and follow the maker's cleaning guide. Run laser test |
| Line appears only when copying or scanning | Mark on scanner or document-feeder glass | Compare a standalone copy with a computer-printed test page. Print control page |
Use plain paper and Normal or Standard quality. A repeatable defect on a known test page rules out a damaged source document.
Use the nozzle check for inkjets. Use the laser test for toner density, repeating marks, and drum-related streaks.
Make a standalone copy, then print the control page from a computer. A line only on copies points to the scanner path, not the print engine.
For an inkjet, run one normal head cleaning. For a laser printer, follow its documented cleaning-page or maintenance procedure. Reprint the same test.
Replace a consumable only when the defect follows that color channel or the printer reports it near end of life. Persistent lines may need manufacturer support.
Often follow print-head passes or paper advance. Test nozzles and alignment first.
Often follows a fixed point in the scanner or print path. Compare copy and print output.
May track a rotating laser-printer component. Measure the repeat distance and consult the service guide.
On an inkjet printer, horizontal white gaps or bands usually point to missing nozzles, low ink, or a print-quality setting. On a laser printer, repeating horizontal bands can indicate toner, drum, transfer, or fuser trouble. Print the matching diagnostic page before replacing a part.
A line in the same vertical position on every page often comes from contamination or damage along the paper path. On a laser printer, the toner cartridge or imaging drum is a common source. Follow the manufacturer cleaning instructions and avoid touching the drum surface.
Yes. Missing ink nozzles produce regular horizontal gaps across photos and color areas. A CMYK nozzle-check pattern makes the affected color channel easier to identify.
If a standalone copy has a line but a page printed from a computer is clean, inspect the scanner glass or narrow document-feeder glass. A small mark on the glass can become a full-length line on every copy or scan.
Run one normal cleaning cycle and print another nozzle check. If the pattern improves, one additional cycle may help. Repeated cleaning consumes substantial ink; stop and consult the printer manual if two cycles produce no improvement.