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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.

426 - 428

Possible hardware fault

Fronius · Symo Advanced Manual

What does 426 - 428 mean?

The inverter has detected a general internal hardware malfunction. This range of codes indicates that a specific hardware component may be faulty, affecting the inverter's operation.

Common Causes

  • Failure of an unspecified internal hardware component
  • Damage to PC boards or internal circuitry

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    If this status code is displayed all the time, notify a Fronius-trained service engineer.

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

Related Faults

102AC voltage too high103AC voltage too low105AC frequency too high
Source: Fronius Symo Advanced Manual
Open Manual (Page 43)Search more codes in this manual