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ErrorLib — Industrial Fault Code Library

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409

UNEXPECTED PCU RESET

Otis · DSD 412 Elevator System

What does 409 mean?

The PCU processor was unexpectedly reset.

Common Causes

  • Incorrect PCU software and revision level.
  • Problem with main circuit card hardware.
  • External noise interference.
  • Improper equipment and signal grounding connections.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify that the correct PCU software and revision level are being used.

  2. 2

    Inspect for external noise interference sources.

  3. 3

    Ensure equipment and signal grounding connections are proper.

  4. 4

    If the problem remains, replace the Drive Control PCB.

Browse all codes in this manual (57)
Verified technical data. Last updated: April 2026

Related Faults

117/118SERIAL COMMUNICATION FAULT400MOTOR OVERLOAD FAULT401EXCESSIVE FIELD CURRENT
Source: Otis DSD 412 Elevator System
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