Canon Printer Error E51 — What It Means & How to Fix It

What Does This Error Mean?

Error E51 on a Canon printer means the printhead alignment procedure failed. Canon printers automatically align the printhead when you install a new cartridge or printhead. E51 appears when the alignment sensor cannot read the alignment test pattern correctly. This usually means the alignment sheet was not fed correctly, the platen glass is dirty, or the alignment sensor has a fault.

Affected Models

Canon PIXMA MG5220
Canon PIXMA MG5320
Canon PIXMA MX882
Canon PIXMA MP560
Canon PIXMA all-in-one series with auto alignment

Common Causes

Alignment test pattern printed on the wrong paper type — requires plain white letter or A4 paper
Dirty platen glass or white reference sheet on the scanner causing misread of the alignment pattern
Paper fed at an angle during the alignment scan
Low ink level in one or more cartridges causing a faint or incomplete alignment pattern
Defective alignment sensor inside the printer that cannot read the printed pattern

How to Fix It

Cancel the current alignment and try again. Make sure you are using plain, bright white letter or A4 paper — not photo paper, colored paper, or recycled paper. Alignment requires a clean white surface to read the pattern.

Recycled or off-white paper can cause E51 because the sensor contrast is insufficient to read the alignment dots.
Check the scanner glass (for all-in-one models). Open the scanner lid and clean the flat glass surface with a soft damp cloth. Also clean the white backing on the inside of the scanner lid.

Dirt on the scanner glass directly affects the alignment sensor reading on many Canon all-in-one models.
Check ink levels. If any cartridge is very low or empty, the alignment pattern will print faintly and the sensor cannot read it accurately. Replace or refill low cartridges before attempting alignment.

Even a nearly empty cartridge may print faint enough to cause E51.
Reload the paper tray with a small stack of fresh paper (5 to 10 sheets) and restart the alignment from Settings > Maintenance > Align Print Head.

A clean paper stack feeds more reliably than a single sheet, which can skew during feeding.
If E51 persists after all the above steps, the alignment sensor inside the printer may have failed. Contact Canon support or a service center for further diagnosis.

A printer that consistently fails alignment should still be able to print — try disabling automatic alignment if your model allows it.

When to Call a Professional

E51 is usually a user-fixable problem involving the alignment process or paper. If cleaning the scanner glass and retrying with fresh paper does not work, the alignment sensor may have failed. Alignment sensor replacement is an advanced repair. For older printers, contact Canon support at 1-800-OK-CANON to discuss repair options.

Frequently Asked Questions

Can I skip the alignment and just print?

On most Canon models you can dismiss the alignment prompt and continue printing. Skipping alignment may result in slightly misaligned text or colors at high print quality settings. For everyday document printing, the difference is barely noticeable. For photo printing, proper alignment makes a visible difference.

How often does alignment need to be done?

Automatic alignment runs once when a new cartridge or printhead is installed. You can also run it manually anytime from the printer's maintenance menu. Most users never need to think about it — the automatic process handles everything.

Why does E51 happen after I install a new cartridge?

Installing a new cartridge triggers an automatic alignment sequence. If the alignment paper is not loaded, is the wrong type, or feeds incorrectly, E51 is the result. Make sure plain white paper is loaded in the main tray before installing new cartridges.