Direct answer
For the Canon MAXIFY GX4020, the exact feed/duplex/output location, media condition and a complete sheet count matter. First, power off and follow the model's documented paper path.
What this covers
- Canon MAXIFY GX4020 (5779C002)
- Canon printer; PIXMA/MegaTank/MAXIFY/imageCLASS ink/toner systems and maintenance paths differ.
- The specific fault this record addresses: shows a paper jam or repeatedly jams
What it does not cover
- ×The same symptom on a different Canon product line, which has its own record and its own cited source
- ×An on-screen error code whose meaning has not been checked against this exact model's manual
- ×Live electrical, gas, sealed-system, internal battery-cell or structural repair — a technician boundary, not a self-service step
Differential
What actually causes this, and how to tell them apart
These are ordered by how often each one is the answer, not by how easy it is to try. The point of the middle column is that two causes producing the same headline symptom rarely produce the same detail — that detail is what tells you which one you have before you change anything.
- 1
Torn paper fragments remain in the path
What separates it Jams recurring immediately after one was cleared.
How to confirm A fragment left behind causes a jam on nearly every subsequent sheet. Open every access door and check the full path with a light rather than only where the sheet was visible.
- 2
The paper guides are not set to the paper
What separates it Sheets feeding crooked, or jamming at the same point every time.
How to confirm Guides must touch the stack without compressing it. Too loose lets sheets skew; too tight stops them feeding.
- 3
The tray is overfilled or the stack is not fanned
What separates it Multiple sheets feeding together, or jams worse with a freshly filled tray.
How to confirm Fan the stack and load below the maximum fill line.
- 4
The paper is damp, curled or previously printed
What separates it Jams with paper stored in a humid place, or when reusing single-sided sheets.
How to confirm Try a fresh ream. Damp and curled paper is a very common cause and is invisible until it jams.
- 5
The pickup rollers are worn or glazed
What separates it Sheets failing to feed at all, or feeding intermittently, on an older printer.
How to confirm Rollers lose grip as they wear and glaze. Cleaning them per the manual restores grip for a time; replacement is the real fix.
- 6
Media is outside the supported weight or size
What separates it Jams only with card, labels, envelopes or unusual sizes.
How to confirm Check the specification, and use the correct tray or manual feed slot for heavy media.
Before you touch a setting
Record this first — changing settings destroys the evidence
Every item below stops existing the moment a reset, re-pair or settings change is made. Written down first, they are what separates the causes above; recovered afterwards, they are guesswork.
- Where the sheet stops — at pickup, mid-path, in the duplexer, or at the exit. Each points at a different part of the mechanism.
- Whether jams began recurring immediately after a previous one was cleared, which points at a fragment left behind.
- Whether the paper is fresh, and how it has been stored.
- Whether it happens with all media or only heavy or unusual stock.
Power the printer off before clearing anything
ReversibleRollers can engage without warning while the printer is powered.
Pull the sheet in the direction of normal paper travel
ReversiblePulling backwards can damage rollers and tears the sheet, leaving fragments that cause every subsequent jam.
Open every access door and inspect the whole path with a light
ReversibleFragments hide outside the area where the sheet was visible, and a single one causes repeat jams indefinitely.
Fan a fresh stack, load below the fill line, and set the guides to touch without compressing
ReversibleToo loose lets sheets skew, too tight stops them feeding.
Clean the pickup rollers per the manual if sheets fail to feed
ReversibleGlazed rollers lose grip with age; cleaning restores it temporarily and replacement is the real fix.
Model-specific
What is true of this model and not of its siblings
Generic advice for the product line fails here. Each item below is a property of this specific model family that changes which of the steps above apply to you.
- Model scope
- 5779C002. Canon printer; PIXMA/MegaTank/MAXIFY/imageCLASS ink/toner systems and maintenance paths differ.
- Type — BUSINESS refillable INK TANK all-in-one (MAXIFY)
- A business MAXIFY MegaTank AIO — refillable ink BOTTLES with pigment inks and office features, below the GX7021 in speed/capacity. Still inkjet, so the printhead can CLOG if unused.
- Pigment ink + volume
- Pigment inks for durable documents; very low running cost. Don't run tanks dry; initial charging uses some starter ink (normal).
- Connectivity
- Wi-Fi/Ethernet/USB via the Canon app; 'offline' is usually a network/queue issue.
- Symptom boundary
- This record covers Canon MAXIFY GX4020 when it shows a paper jam or repeatedly jams. A different symptom on the same hardware, or this symptom on a different Canon product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
Continuing past any one of these costs more than the repair saves — in safety, in warranty, or in evidence a technician needs.
- !Never reach into the fuser area of a laser printer without letting it cool — it operates at temperatures that cause serious burns.
- !Stop for grinding, broken gears, or a fragment that cannot be reached, and do not force a stuck mechanism.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Where the manufacturer's article stops. Canon publishes this as "Clear a Paper Jam Inside the Printer - TS3720 / TS3722". Step-by-step removal from inside the printer including the torn-paper case that makes the jam message repeat. Probed 2026-08-21: title-verified. What that article does not carry is the model boundary — it is written for a product line, and 5779C002 is the scope applied here. Where a control label, terminal, indicator pattern or reset sequence differs on your unit, the manual for that exact model is the authority, not this page and not the article.
Exact questions
Common follow-ups
My Canon MAXIFY GX4020 prints faded with full ink tanks.+
That is a printhead clog — the MAXIFY is a refillable inkjet, so full tanks do not prevent clogs, especially if it has been idle. Run the nozzle check then Cleaning and, if needed, Deep Cleaning from the menu/software, printing a pattern after each to gauge improvement. Make sure no tank was run dry (air in the lines clogs it). Print regularly to keep the head clear. The pigment ink and tank refills keep running costs very low for office use.
I cleared a jam and now it jams every single time.+
There is almost certainly a torn fragment still in the paper path. Power the printer off, open every access door, and check the whole path with a light — not just where the jammed sheet was. One small piece left behind will jam nearly every subsequent sheet, and it is easy to miss because it is usually not where the jam appeared.
Which way should I pull a jammed sheet?+
In the direction the paper normally travels. Pulling it backwards can damage the rollers and is much more likely to tear the sheet, which leaves fragments behind and turns one jam into a recurring problem. Power the printer off first, since rollers can engage without warning.
Does this answer apply to every Canon model?+
No. It is scoped to 5779C002. Canon printer; PIXMA/MegaTank/MAXIFY/imageCLASS ink/toner systems and maintenance paths differ.
What should I record before troubleshooting paper jam or jamming?+
Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.
Why is a factory reset not the first step?+
A reset can erase accounts, networks, maps, schedules or preferences without distinguishing paper jam, jamming. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Unplug before reaching inside; avoid hot fuser areas, sharp parts and torn-force removal.
Answer for the exact device and software version shown above.