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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.

21

CPU fault

SEW Eurodrive · MOVIFIT-FC Inverter

What does 21 mean?

An internal CPU fault has occurred within the unit. This indicates a general internal processing error, which might be transient or indicate a more serious hardware issue.

Common Causes

  • CPU internal clock synchronization error.
  • Clock generator failure within the CPU.
  • Timer overflow or underflow within the CPU.
  • Critical timing sequence violated.
  • Parameter P0010 (frequency base) causing CPU issue.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Reset the fault by switching off the DC 24 V supply voltage.

Browse all codes in this manual (26)
Verified technical data. Last updated: April 2026

Related Faults

01Overcurrent in output stage04Thermal overload of motor / Overcurrent in brake chopper06Phase failure
Source: SEW Eurodrive MOVIFIT-FC Inverter
Open Manual (Page 126)Search more codes in this manual