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: March 2026

Related Faults

Source: Mitsubishi Electric R410A Systems