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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.

E51

Inverter PCB Fault / Power Transistor Overheat

Mitsubishi Electric · R410A Systems

What does E51 mean?

The inverter PCB is faulty, or the power transistor module on the inverter has overheated. This indicates a problem with the inverter's control or power section, which drives the compressor, potentially leading to compressor malfunction.

Common Causes

  • Inverter's main control board has malfunctioned.
  • Power transistor within the inverter has overheated and failed.
  • Overload condition leading to excessive current draw and component overheating.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the inverter PCB for any visible signs of damage, such as burn marks, swollen capacitors, or blown components.

  2. 2

    Check the inverter's heatsink for cleanliness and ensure proper airflow; verify inverter cooling fan operation.

  3. 3

    Measure compressor current to identify potential overloads contributing to transistor overheat.

  4. 4

    Verify voltage supply to the inverter PCB is stable and correct.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

E0Transmitting/Receiving Signal ErrorE112Auto Addressing Conflict / Factory Address Setting ErrorE14Master/Slave System Configuration Error
Source: Mitsubishi Electric R410A Systems
Open Manual (Page 5)Search more codes in this manual