Centauri Carbon: self-test stuck at «Input Shaping» or error 401 (accelerometer)

Symptom

During the first-use self-test, or when calibrating Input Shaping manually, the Centauri Carbon screen stays stuck on the Input Shaping step and does not continue, or shows «401 Accelerometer chip error».

Likely causes, from most to least likely

1. The three screws that hold the bed for shipping have not been removed.
2. The bed tilted during shipping and the Z axis rises with too much resistance.
3. The frame was deformed during shipping.
4. The Z motor connector is loose.
5. Error 401: loose X/Y belts or, otherwise, a faulty accelerometer (the extruder communication board may be failing).

Checks to tell which one it is

• Check that you have removed the three bed fixing screws.
• Place the glass cover on top and open and close the door: if they do not line up with the top frame, the frame may be deformed.
• With the printer switched off and unplugged, check whether the bed rises smoothly when you pull the Z belt by hand (you need to lay the printer on its side and remove the bottom cover).

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. Remove the shipping screws

   If any of the three bed fixing screws is still in place, remove it and repeat the self-test.

   Check: The self-test gets past the Input Shaping step.

   If that does not fix it: Check the frame (next step).

2. Deformed frame

   If the glass cover or the door do not line up with the frame, take clear photos and contact Elegoo support; do not take anything else apart.

   Check: Support confirms whether parts need replacing.

   If that does not fix it: Follow their instructions.

3. Stiff Z axis or loose connector

   With the printer off and unplugged, lay it on its side and remove the ten bottom cover screws (2.0 mm key). Pull the Z belt by hand: if the bed rises with resistance, check whether it is tilted, grease the Z rails with white lithium grease and adjust the bed following Elegoo's video. If it rises smoothly, disconnect and reconnect both ends of the Z motor cable.

   Check: The bed rises smoothly and the self-test completes.

   If that does not fix it: If the warning is 401, tension the belts (next step).

4. Error 401: tension the X/Y belts

   Switch off and unplug. Loosen, without removing, the four X/Y tensioner screws with the 2.0 mm key. Move the toolhead to all four corners: the tensioners are spring-loaded and the belts tighten themselves. Tighten the screws, power on and repeat the self-test or Input Shaping calibration.

   Check: Calibration completes without 401.

   If that does not fix it: The extruder communication board may be faulty: contact Elegoo support with a video of the error, another of homing, the firmware version and the serial number.

Prevention

• When unboxing, remove the three bed shipping screws before powering on.
• Check belt tension if you hear noises or after replacing toolhead parts.
• Keep the Z rails greased if the bed starts to rise with effort.

Still not fixed?

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Printers it applies to

Elegoo Centauri Carbon.

Official sources

This guide summarises the official documentation linked here:

• Fails at the Input Shaping Step During Self-Test (Centauri Carbon) · Elegoo
• Error Code: 401 Accelerometer chip error (Centauri Carbon) · Elegoo
• How to Adjust the Belt Tensioner (Centauri Carbon) · Elegoo