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ErrorLib — Industrial Fault Code Library

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401

Drive Ready Signal (DRDY) Lost

Fanuc · Alpha i series AC Servo Motor

What does 401 mean?

The DRDY (Drive Ready) signal has transitioned to 0, indicating that the servo amplifier is not in a ready state. This often occurs during initial power-up or after a fault, preventing motor operation.

Common Causes

  • Servo amplifier internal readiness conditions not met.
  • Initial power-up sequence not completed or interrupted.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Cycle power to the servo amplifier.

  2. 2

    Verify power supply stability and input voltage levels for the servo amplifier.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

000Power-Down Required Parameter011Zero Feedrate Specified013Maximum Feedrate Zero
Source: Fanuc Alpha i series AC Servo Motor
Open Manual (Page 226)Search more codes in this manual