HVAC Toolkit
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Mitsubishi Heavy Industries Error Codes

Inverter Mini-Splits & Air Conditioners ยท Japan

Prefixes: E=System/Sensor, F=Sensor/Protection, P=Protection, H=Status

E-Series (System/Sensor Errors)

Code Description Possible Cause Action
E01 Remote controller communication error Wired remote controller wiring failure Check remote controller wiring connections
E02 Duplicate indoor unit address Multiple units have same address Assign unique address to each indoor unit
E03 Indoor/outdoor communication error Communication not established Check wiring between indoor and outdoor units
E05 Indoor/outdoor transmission abnormal Serial communication failure Check communication line polarity and connections
E06 Indoor heat exchanger thermistor error Evaporator sensor fault Check/replace evaporator thermistor
E07 Indoor return air thermistor error Room temperature sensor fault Check/replace return air thermistor
E08 Heating overload protection Overheat during heating mode Check airflow, thermistor operation
E09 Drain float switch activated Condensate drain blocked Clean drain line, check float switch
E10 Too many indoor units connected Over 17 indoor units on system Reduce number of connected units
E16 Indoor fan motor error Fan motor failure or locked rotor Check fan motor, capacitor, wiring
E28 Remote controller thermistor error Remote controller sensor fault Replace remote controller
E32 Phase wiring open or reversed 3-phase connection error Check phase wiring, correct phase sequence
E33 Inverter current abnormal Compressor current out of range Check compressor, inverter board
E34 L3-phase wiring open Missing phase connection Check 3-phase power supply connections
E35 Heat exchanger temperature high Condenser overheat Clean condenser, check fan operation
E36 Discharge temperature abnormal Compressor discharge overheat Check superheat, refrigerant charge
E37 Outdoor heat exchanger thermistor error Condenser thermistor fault Check/replace condenser thermistor
E38 Outdoor air thermistor error Ambient temperature sensor fault Check/replace outdoor air thermistor
E39 Discharge pipe thermistor error Discharge temperature sensor fault Check/replace discharge thermistor
E40 High pressure protection High pressure switch activated Check condenser, fan, refrigerant charge
E42 Compressor overcurrent Compressor drawing excess current Check compressor, power supply, refrigerant
E43 Low pressure protection Low pressure switch activated Check refrigerant charge, filter, expansion valve
E47 Inverter overvoltage DC bus voltage too high Check power supply voltage, inverter board
E48 DC fan motor abnormal Outdoor DC fan motor fault Check fan motor, hall sensor, wiring
E52 Control circuit abnormal Outdoor PCB fault Check/replace outdoor control board
E56 Power transistor thermistor error IPM temperature sensor fault Check IPM thermistor, replace if needed
E57 Insufficient refrigerant Low refrigerant charge detected Check for leaks, recharge system
E59 Compressor startup error Compressor failed to start Check compressor, inverter, wiring
E60 Compressor position detection error Rotor position sensor fault Check compressor, inverter board
E63 Emergency stop activated Emergency stop input received Check emergency stop circuit, reset
E64 High pressure protection (sensor) High pressure transducer trip Check condenser, refrigerant, ambient
E68 Current sensor abnormal CT sensor fault Check current transformer sensor

Mitsubishi Heavy Industries Troubleshooting Tips

Before Calling for Service

  • Turn off unit, wait 5 minutes, then restart - some errors auto-reset
  • Check and clean air filters - many errors caused by restricted airflow
  • Verify power supply voltage is within specification
  • Check circuit breaker and disconnect switch
  • Note the exact error code and when it occurs for technician

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