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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.

E43

Max Indoor Units Exceeded

Mitsubishi Electric · R410A Systems

What does E43 mean?

The number of indoor units connected to a single outdoor unit exceeds the system's specified design capacity. This will prevent proper communication and operation, potentially leading to system instability.

Common Causes

  • Maximum number of indoor units configured exceeds system capacity.
  • Incorrect DIP switch settings for indoor unit addressing.
  • Control board does not recognize a newly added indoor unit.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Count the number of physically connected indoor units and compare this against the outdoor unit's specified maximum capacity.

  2. 2

    Verify system design against Mitsubishi Heavy Industries technical documentation for the specific outdoor unit model and configuration.

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 4)Search more codes in this manual