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ErrorLib — Industrial Fault Code Library

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E56

Power Transistor Thermistor Faulty or Disconnected

Mitsubishi Electric · FR-D700 Inverter

What does E56 mean?

The power transistor thermistor is faulty or disconnected (specific to FDCVA151-251 models), impacting temperature monitoring of the power transistors. This can lead to inverter damage from overheating.

Common Causes

  • Disconnection of the power transistor thermistor.
  • Open circuit fault in the power transistor thermistor sensor.
  • Faulty power transistor thermistor indicating an incorrect temperature.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the power transistor thermistor connection for dislodgement or damage, particularly on FDCVA151-251 models.

  2. 2

    Measure the resistance of the thermistor to verify functionality and compare to the specified temperature-resistance chart.

  3. 3

    Ensure the thermistor is securely connected to the inverter PCB and properly seated for accurate temperature sensing.

Browse all codes in this manual (78)
Verified technical data. Last updated: April 2026

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Source: Mitsubishi Electric FR-D700 Inverter
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