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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.

MT

Maintenance timer

Mitsubishi Electric · Mitsubishi FR-E800 Variable Frequency Drive

What does MT mean?

This indicator appears when the inverter's cumulative energization time reaches or exceeds the value set in parameter Pr.504. It serves as a reminder that routine maintenance may be due for the equipment.

Common Causes

  • Cumulative energization time has reached the threshold set in Pr.504 (Maintenance timer setting).
  • Environmental conditions (e.g., high temperature, dust) accelerate component wear, making maintenance due earlier than anticipated.
  • Cooling fan operating hours exceeding recommended service life.
  • Electrolytic capacitor aging approaching end-of-life.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Record the current operating hours displayed (e.g., Pr.504 related monitor value) for historical tracking.

  2. 2

    Inspect cooling fans for bearing noise, reduced airflow, or physical damage, and clean or replace if necessary.

  3. 3

    Clean inverter heatsinks and cooling passages to ensure optimal heat dissipation.

  4. 4

    Visually inspect electrolytic capacitors on the main circuit board for bulging or leakage.

  5. 5

    Reset Pr.504 (Maintenance timer setting) after completing maintenance tasks.

Browse all codes in this manual (55)
Verified technical data. Last updated: April 2026

Related Faults

CFContinuous operation during communication faultDIPDuplicate IP addressE.1Option Fault / Internal Contact Failure
Source: Mitsubishi FR-E800 Variable Frequency Drive
View Official PDFSearch more codes in this manual