CodeRegistry
Brands
  1. Home
  2. Mitsubishi Electric
  3. Air Conditioning
  4. E4
About·Privacy·Terms

CodeRegistry — Your global library for technical solutions.

For your safety: always follow the equipment manufacturer’s official manuals. CodeRegistry is an independent help site and is not affiliated with the brands listed here.

E4

E4 - Receiving Error (PAR W21)

Mitsubishi Electric · Air Conditioning

What does E4 mean?

This error signifies a receiving error within the PAR W21 system, likely due to incorrect refrigerant address settings on the Ecodan.

Common Causes

  • Incorrect refrigerant address setting on SW1
  • Communication issues within the Ecodan system
  • Faulty Ecodan controller

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the refrigerant address setting on SW1 of the Ecodan.

  2. 2

    Check communication wiring integrity.

  3. 3

    Restart the Ecodan system.

  4. 4

    Refer to the Ecodan documentation for troubleshooting steps.

Browse all codes in this manual (170)
Verified technical data. Last updated: April 2026

Related Faults

0.5-second ON / 0.5-second OFF blinkUpper lamp blinks 0.5-second ON/OFF - Miswiring or serial signal error00Normal operation - No error codes1 beep during error display mode1 beep during error display mode - Unit has an error (different code)
Source: Mitsubishi Electric Air Conditioning
Open Manual (Page 35)Search more codes in this manual