Error 704 on the Elegoo Centauri Carbon 2 Combo means the printer failed to complete its homing sequence. Homing is a mandatory startup step where each axis moves to its reference position, and a failure here prevents the printer from knowing where the toolhead is — so it halts rather than risk a crash or mis-print.

What the Error Means

During homing, the firmware drives each axis until it receives a trigger signal from an endstop switch or from the leveling probe, then zeros its position counter at that point. Error 704 fires when one of those trigger signals does not arrive within the expected travel range — meaning either the axis is mechanically blocked, the endstop or probe connector is loose, or the sensor itself has failed. On the Centauri Carbon 2 Combo, Z-axis homing relies on the probe-based leveling sensor to detect the bed surface, so a probe connectivity issue can trigger this error even if the physical axis moves freely.

Step-by-Step Fix

1. Inspect the print area for obstructions before attempting to home. Remove any tools, printed parts, or filament fragments from the bed and from the toolhead travel path.
2. Power off the printer and reseat all endstop and probe wiring connectors — check both the toolhead end and the motherboard end for each connector.
3. Move each axis by hand (with the printer powered off) through its full travel range to confirm nothing is binding or scraping. Check belt tension on the X and Y axes — a slack belt can prevent the axis from homing properly.
4. Power on and attempt homing again from the touchscreen. Watch which axis triggers the error to narrow down which sensor is at fault.
5. Verify probe or endstop trigger alignment: on Z homing, confirm the leveling probe is positioned correctly to contact the bed. On X/Y, verify the limit switch or optical flag is aligned with its trigger actuator.
6. If the error persists, trace the relevant axis cable for damage and contact Elegoo support if the endstop, probe, or a stepper motor connector shows signs of damage.

Parts Required

• No replacement parts are typically required for this fix — basic tools only
• Replacement endstop switch or leveling sensor (only if confirmed failed)

Contact Elegoo support if homing fails repeatedly after all mechanical checks pass — a motherboard input fault may need assessment.

Frequently asked questions

What does Elegoo 704 mean?

Error 704 on the Elegoo Centauri Carbon 2 Combo means the printer failed to complete its homing sequence. Homing is a mandatory startup step where each axis moves to its reference position, and a failure here prevents the printer from knowing where the toolhead is — so it halts rather than risk a crash or mis-print.

How do I fix Elegoo 704?

Elegoo error 704 means the Centauri Carbon 2 Combo failed to home correctly. Learn to clear obstructions, check endstop and probe wiring, and verify axis alignment.