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Fronius · PV inverters · Fronius Symo 3.0–20.0 (three-phase grid inverter, SnapINverter)

STATE 401Unable to communicate with the power stage set

Name in the manufacturer's documentation (service manual): Unable to communicate with the power stage set[1]

In plain words (editorial)

The control unit cannot communicate with the power stage set inside the inverter. The inverter tries to reconnect automatically and resumes feeding energy into the grid if possible.

When to call a service technician: If the code is displayed all the time, notify a Fronius-trained service technician.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 016-24082016) – distributor copy (42,0410,2028 (016-24082016)) , p. 46 manufacturer document – copy from a distributor quote verified 401 Unable to communicate with the power
  2. [2] Fronius Symo / Fronius Eco – Operating Instructions (e-Manual HTML), Version 044-17072025 – chapter “Status diagnostics and troubleshooting” (text capture) (e-Manual 4204101909, 044-17072025) , p. 4 official manufacturer document quote verified If the status code is displayed all the time: notify a Fronius-trained service technician
  3. [3] Fronius Symo / Fronius Eco – Operating Instructions (e-Manual HTML), Version 044-17072025 – chapter “Status diagnostics and troubleshooting” (text capture) (e-Manual 4204101909, 044-17072025) , p. 4 official manufacturer document quote verified The inverter will automatically attempt to connect again and, if possible, will resume feeding energy into the grid