448 on a Fronius International GmbH Fronius SnapINverter: Neutral conductor not connected
Short answer
On a Fronius International GmbH inverter, 448 means: Neutral conductor not connected. 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: Neutral conductor not connected.
Part involved: AC wiring / RCMU.
When it shows: Class 4 status code.
Likely causes:
- Inverter not feeding in (474/475); if recurring contact your system engineer.
Is it safe?
| Does the inverter stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: unknown.
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.
- Contact your installer.
What the engineer will check
- Insulation-resistance test of PV strings (per string), inspect DC cabling/connectors for damage/water ingress; check neutral connection (448).
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