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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.

303

DC module overtemperature

Fronius · Symo Advanced Manual

What does 303 mean?

The DC power module within the inverter has exceeded its safe operating temperature. This triggers a short-term interruption in energy feeding, and the inverter will then attempt to resume operation once the temperature drops.

Common Causes

  • Restricted airflow to the inverter's cooling elements
  • Accumulation of dust or debris on cooling air openings or heat sink
  • High ambient temperature exceeding inverter specifications

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Purge the cooling air openings and heat sink to ensure proper airflow.

  2. 2

    If this status code keeps recurring after cleaning, contact your system engineer for further inspection.

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 42)Search more codes in this manual