If your Elegoo Centauri Carbon says “abnormal Z axis motor”, don't immediately assume the Z-axis motor is dead. This error normally shows up when the printer has trouble homing the Z axis or moving the bed correctly.
Restart and Check the Z Axis First
The first thing I'd do is completely power the Centauri Carbon off, unplug it for a minute, and turn it back on.
Then try homing the printer again and actually watch what happens.
If the bed tries to move but gets stuck, makes a grinding noise, or moves strangely, check around the Z-axis lead screws and belt for anything physically stopping it.
Check the Z-Axis Motor Connection
A loose connection can also cause the Centauri Carbon abnormal Z axis motor error.
Elegoo's troubleshooting recommends powering the printer off and checking/reseating the Z-axis motor cable. If the connection isn't making good contact, the printer may think there's something wrong with the motor even though the motor itself is fine.
It Might Not Actually Be the Motor
This is the big thing to know.
An abnormal Z-axis motor error doesn't automatically mean you need to buy a new motor. The problem can also come from the Z-axis limit switch, wiring, or motherboard.
If the nozzle keeps trying to push into the build plate while homing, Elegoo points toward the limit switch or its connection as a possible problem. If the Z axis won't move or keeps jamming, the motor, cable, or motherboard could be responsible.
Check if the Bed Is Stuck
With the printer powered completely off and unplugged, check that nothing is binding the Z-axis system.
I've also seen Centauri Carbon owners report this error after very tall prints where the bed ended up near the bottom of its travel. In at least one case, manually freeing the Z-axis mechanism got the printer moving again. That's anecdotal rather than an official Elegoo fix, but it's worth checking before you start replacing parts.
Still Getting the Error?
If you've restarted the printer, checked for anything physically stuck, and reseated the Z-axis connection but you're still getting the error, I'd contact Elegoo support before buying parts.
The actual Z-axis motor may be bad, but the limit switch or motherboard can create basically the same symptoms. I'd want to figure out which part is actually causing the problem before spending money replacing the motor.