What is the root cause of the nozzle not sensing the Z1 axis origin sensor (PLC2-X0) error in KM-ASSYM5-05?

What steps can be taken to troubleshoot and resolve the error?

Is there a specific setting or
The solution to the M127 error "Nozzle 1 does not sense the Z1 axis origin sensor (PLC2-X0)" would involve troubleshooting the Z1 axis sensor on PLC2-X0