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ErrorLib — Industrial Fault Code Library

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1020

SFC Program End Error

Mitsubishi Electric · MELSEC System Q/L Series

What does 1020 mean?

The SFC (Sequential Function Chart) program cannot be terminated normally. This issue may be caused by electrical noise interference or other unspecified reasons preventing the SFC program from concluding its execution sequence.

Common Causes

  • SFC program cannot be normally terminated due to noise.
  • SFC program cannot be normally terminated for any other reason.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Implement noise reduction measures for the control system environment.

  2. 2

    Reset the CPU module and attempt to RUN it again.

  3. 3

    If the same error is displayed again after resetting, diagnose for a CPU module hardware fault.

Browse all codes in this manual (53)
Verified technical data. Last updated: April 2026

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1000CPU Down Error1001CPU Down Error with Device Access Issue1002CPU Down Error
Source: Mitsubishi Electric MELSEC System Q/L Series
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