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E9 (6811)

Indoor/Outdoor Unit Communication Error (Outdoor Transmitting)

Mitsubishi Electric · PUZ-HA30/36NHA4 Outdoor Unit

What does E9 (6811) mean?

The outdoor controller circuit board detects '0' receiving 10 times continuously despite transmitting '1', or it fails to find a blank transmission path for 10 minutes. This indicates potential contact failure or looseness in the indoor/outdoor unit connecting wire, a defective communication circuit on the outdoor controller circuit board, or noise interference in the power supply or connecting wire.

Common Causes

  • Outdoor unit fails to transmit communication signals to indoor unit.
  • Damaged or disconnected communication wiring between units.
  • Faulty outdoor unit control board.
  • Interference on the communication line.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check for disconnection or looseness of the indoor/outdoor unit connecting wire.

  2. 2

    Turn the power off, then on again. If the abnormality reappears, replace the outdoor controller circuit board.

Browse all codes in this manual (45)
Verified technical data. Last updated: April 2026

Related Faults

01Overvoltage Error02Undervoltage Error04L1 or L2-Phase Open Error
Source: Mitsubishi Electric PUZ-HA30/36NHA4 Outdoor Unit
Open Manual (Page 30)Search more codes in this manual