Homing Failed / Endstop Not Triggered
Marlin 3D Printer Firmware
Severity: ModerateWhat Does This Error Mean?
Homing Failed means the printer moved an axis to find the endstop but never triggered it. The axis reached its maximum travel distance without hitting the endstop switch. Check the endstop switch, its wiring, and make sure nothing is blocking the axis.
Affected Models
- All Marlin-based 3D printers with physical endstops
Common Causes
- Endstop switch broken or not clicking
- Endstop wiring disconnected from the mainboard
- Endstop mounted too far — axis cannot reach it
- Mechanical obstruction preventing the axis from moving
- Wrong endstop configuration in firmware (normally open vs normally closed)
How to Fix It
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Manually trigger the endstop switch and listen for a click.
Press the endstop lever with your finger. You should hear a click. If no click, the switch is broken.
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Check the endstop wiring on the mainboard.
Make sure the endstop plug is in the correct port and fully seated. Swapped ports (X in Y slot) cause homing to fail.
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Use M119 to check endstop status.
Send M119 via a terminal. It reports each endstop as TRIGGERED or open. Manually press each endstop and send M119 again to confirm it changes state.
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Check for mechanical obstructions.
Move each axis by hand (with power off). They should move freely. Look for loose screws, cables, or debris blocking the path.
Frequently Asked Questions
What is homing?
Homing moves each axis until it hits its endstop switch. This tells the printer where zero is (the home position). The printer must home before it can print accurately.
What is the difference between normally open and normally closed endstops?
Normally open (NO): circuit is open until pressed. Normally closed (NC): circuit is closed until pressed. NC is safer because a broken wire is detected as a trigger, preventing crashes.