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ErrorLib — Industrial Fault Code Library

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939

Faulty Field Control Hardware.

Otis · DSD 412 Elevator System

What does 939 mean?

This fault indicates a problem with the field control hardware. It may only occur during the power-up sequence.

Common Causes

  • Component problem with the Field Interface Board.
  • Component problem with the Main Control Board.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Replace the Field Interface Board.

  2. 2

    If the fault is still present after replacing the Field Interface Board, replace the Main Control Board.

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
Open Manual (Page 92)Search more codes in this manual