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ErrorLib — Industrial Fault Code Library

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256–258

Power EEPROM data defective or too old

Danfoss · VLT AutomationDrive FC 301/302

What does 256–258 mean?

The data stored in the power EEPROM (Electrically Erasable Programmable Read-Only Memory) is either corrupted, unreadable, or outdated. This can compromise the drive's ability to operate correctly by affecting stored parameters or configuration.

Common Causes

  • Data corruption in the power EEPROM caused by voltage transients or power fluctuations during a write operation.
  • Degradation or end-of-life of the EEPROM memory cells, leading to unreliable data storage and retrieval.
  • Firmware incompatibility where the main control board's firmware requires a newer EEPROM data structure than what is present.
  • Failed write operation to the EEPROM during a parameter save or firmware update.
  • External electromagnetic interference (EMI) disrupting the EEPROM read/write cycles.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Perform a full power cycle of the drive by disconnecting input power for at least 60 seconds, then reapply power.

  2. 2

    2. Attempt to clear the fault by accessing parameter P16-90 (Fault Log) and selecting the 'Clear All Faults' option.

  3. 3

    3. Update the drive's main firmware to the latest compatible version (e.g., using a dedicated flash tool or SD card) which may include EEPROM data structure updates.

  4. 4

    4. Execute a drive parameter backup (if possible) and then a factory reset (P8-01 to [1] Factory reset) to reinitialize EEPROM data, then restore parameters.

  5. 5

    5. Check the stability of the drive's auxiliary control power supply (e.g., 24VDC at terminal X1/1 and X1/2) for voltage fluctuations during operation.

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Verified technical data. Last updated: April 2026

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Source: Danfoss VLT AutomationDrive FC 301/302
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