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ErrorLib — Industrial Fault Code Library

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00

Communication Error (Indoor/Outdoor/Remote Controller)

Mitsubishi Electric · PAR-21MAA MA Remote Controller

What does 00 mean?

A communication error exists within the system, potentially due to an open or shorted remote controller transmission wire (S1, S2, S3), or an outdoor unit configured with an address other than 0. The outdoor board LED shows only green after startup, and the remote controller may have no display or its display may quickly disappear.

Common Causes

  • General communication error between indoor, outdoor, or remote controller units.
  • Wiring issues (open, short, high resistance) on the communication line.
  • Incorrect communication protocol or baud rate settings.
  • One or more devices on the communication network have failed.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the continuity and integrity of the remote controller transmission wire (S1, S2, S3) between the indoor and outdoor unit using a multimeter, checking for both open circuits and short circuits.

  2. 2

    Check the outdoor unit's address setting; ensure the indoor unit is configured to connect to an outdoor unit with address '0'.

  3. 3

    Verify that all remote controller transmission wire connections at the terminal blocks (S1, S2, S3) are secure and correctly wired with proper polarity.

Browse all codes in this manual (26)
Verified technical data. Last updated: April 2026

Related Faults

----No Error HistoryA0~A8M-NET System Communication ErrorE0Outdoor Unit Communication Transmit Error
Source: Mitsubishi Electric PAR-21MAA MA Remote Controller
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