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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.

P3

System Error (Transmitting/Receiving Signal)

Mitsubishi Electric · R410A Systems

What does P3 mean?

A communication error exists within the system, specifically related to transmitting or receiving signals between components. This impedes control and feedback, causing operational issues.

Common Causes

  • Loss of communication signal between indoor and outdoor units.
  • Interference on the communication line.
  • Faulty communication board on either unit.
  • Incorrect wiring of communication terminals.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect communication wiring connections on both indoor and outdoor unit PCBs for secure seating and damage.

  2. 2

    Verify that DIP switch settings for communication addresses are unique and correctly configured.

  3. 3

    Check for external electrical noise sources near communication lines that could interfere with signals.

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
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