Solar · Error codes · Fronius International GmbH
431Fronius International GmbH · Fronius SnapINverter (Primo, Symo, Eco, Symo Hybrid)
431 on a Fronius International GmbH Fronius SnapINverter: Software problem
Short answer
On a Fronius International GmbH inverter, 431 means: Software problem. The inverter stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Software problem.
Part involved: firmware.
When it shows: Class 4 status code.
Likely causes:
- Inverter not feeding in; perform AC reset (switch automatic circuit breaker off and on again); update inverter firmware; if displayed all the time notify Fronius-trained service engineer.
Is it safe?
| Does the inverter stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: See engineer checks.
What you can check
- Read the state code on the inverter display or in Fronius Solar.web and note date/time for your installer.
- Fronius lists an 'AC reset' for this code: switch the inverter's automatic circuit breaker off and on again (homeowner-accessible breaker in the consumer unit).
- If it persists, contact installer.
What the engineer will check
- Update inverter firmware; Fronius Service.
Who to ask for: Fronius-trained PV installer / Fronius Service Partner.
Certification: Qualified electrician (BS 7671; MCS-certified PV installer for work on the PV array/DC side).
What you might notice
Sources
- Fronius Primo 3.0-1 - 8.2-1 Operating Instructions (HTML) ↗ · 42,0410,2165 online edition · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026