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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

E5SI-T3

Watchdog Timer Error

Yaskawa · Drive Fault Codes

What does E5SI-T3 mean?

A Watchdog Timer Error indicates that the drive's internal processor has stopped responding or is executing an endless loop. This is a critical software or hardware fault preventing safe operation and indicates damaged hardware requiring power cycling and replacement to restore functionality.

Common Causes

  • Processor lock-up due to a software anomaly or firmware bug
  • Faulty hardware component causing the processor to halt or malfunction
  • Severe electrical noise or interference interfering with processor operation.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Perform a power cycle by disconnecting and reapplying input power to the drive.

  2. 2

    Isolate the drive from noisy electrical environments or sources of electromagnetic interference.

  3. 3

    If the fault persists, the drive's control board or the entire unit likely requires replacement by a qualified technician.

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

Related Faults

CEMEMOBUS/Modbus Communication ErrorCPF02A/D Conversion ErrorCPF03Control Board Connection Error
Source: Yaskawa Drive Fault Codes
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