Mitsubishi Electric Aircon Error Codes

Learn what common Mitsubishi Electric error codes mean, what typically causes them, and whether they need urgent attention.

Mitsubishi Electric code table

This is a guidance table, not a model-exact diagnosis. The same code can differ by series, controller, and model year. Use this page to narrow next steps, then verify with model sticker details.

Safety warning

Stop using the unit and contact a technician if the breaker trips repeatedly, you smell burning, see sparks, hear loud electrical buzzing, or water is leaking from places it normally should not.

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E0/E3Communication

Remote controller transmission error

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E1Communication

Wired remote controller communication fault

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E1/E2Communication

Remote controller control board error

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E4/E5Communication

Remote controller signal receiving error

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E5Communication

Indoor and outdoor transmission fault

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E6/E7Communication

Indoor and outdoor communication fault

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E8/E9/ECCommunication

Outdoor transmission error

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E9Indoor

Drain or condensate abnormal

Indoor fan or drain mechanism fault · Indoor PCB or drive circuit abnormality · Loose connectors or internal wiring issue · Water drainage blockage or float-switch problem

E16Indoor

Indoor fan motor abnormal

Indoor fan or drain mechanism fault · Indoor PCB or drive circuit abnormality · Loose connectors or internal wiring issue · Water drainage blockage or float-switch problem

E35Outdoor

High pressure or heat exchanger overheat protection

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

E36System

Compressor overheat or setting error

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

E37Sensor

Outdoor air temperature sensor fault

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

E38Sensor

Outdoor heat exchanger sensor fault

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

E39Sensor

Outdoor discharge pipe sensor fault

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

E40Outdoor

Heating high pressure protection

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

E41Outdoor

Low pressure or pressure abnormal

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

E42Inverter

Compressor overcurrent protection

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

E45Communication

Inverter sub PCB communication fault

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E47Inverter

Current cut or inverter overcurrent event

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

E48Outdoor

Compressor startup failure

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

E51Inverter

Compressor or inverter startup abnormal

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

E53System

Refrigerant shortage or suction side abnormal

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

E54Outdoor

Pressure sensor or outdoor fan system fault

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

E57Inverter

Active filter or power circuit fault

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

E58Inverter

Compressor startup trouble or current safety stop

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

E59Communication

Indoor and outdoor communication trouble at startup

Loose or damaged interconnection or controller wiring · Poor terminal contact or connector corrosion · Indoor or outdoor PCB communication circuit fault · Power supply instability

E60System

Electronic expansion valve fault

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

EA/EBSystem

Miswiring or disconnect between indoor and outdoor

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

EESystem

Indoor and outdoor combination or communication abnormal

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

F3/F5Sensor

Outdoor condenser temperature abnormal

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

F6/F8Sensor

Outlet or discharge temperature abnormal

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

FBIndoor

Indoor control system error

Indoor fan or drain mechanism fault · Indoor PCB or drive circuit abnormality · Loose connectors or internal wiring issue · Water drainage blockage or float-switch problem

L9Inverter

Compressor lock or startup failure

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

P1Sensor

Indoor room thermistor abnormal

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

P2/P9Sensor

Indoor pipe thermistor abnormal

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

P4Sensor

Drain sensor abnormal

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

P5Indoor

Drain pump or overflow protection abnormal

Indoor fan or drain mechanism fault · Indoor PCB or drive circuit abnormality · Loose connectors or internal wiring issue · Water drainage blockage or float-switch problem

P6System

Coil freeze or overheat protection active

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

P7System

Address or setting error

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

P8Outdoor

Pipe temperature abnormal or compressor heat load high

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

PAIndoor

Forced compressor stop due to water leakage abnormality

Indoor fan or drain mechanism fault · Indoor PCB or drive circuit abnormality · Loose connectors or internal wiring issue · Water drainage blockage or float-switch problem

PBIndoor

Indoor fan motor fault

Indoor fan or drain mechanism fault · Indoor PCB or drive circuit abnormality · Loose connectors or internal wiring issue · Water drainage blockage or float-switch problem

PLSystem

Refrigerant circuit abnormal

Control setting or addressing mismatch · Refrigerant circuit imbalance or shortage · Protection logic triggered by abnormal operating conditions · System control board configuration or logic fault

U1/UDOutdoor

High pressure or overheat protection

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

U2Outdoor

High discharge temperature or refrigerant abnormal

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

U3Sensor

Discharge thermistor open or short

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

U4Sensor

Outdoor thermistor open or short

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

U5Sensor

Inverter heatsink temperature abnormal

Thermistor or sensor open or short circuit · Loose sensor connector or damaged harness · Control PCB sensor input fault

U6Inverter

Compressor overcurrent or power module abnormal

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

U7Inverter

Low discharge superheat abnormal

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

U8Outdoor

Outdoor fan protection stop

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

U9/UHInverter

Voltage or current sensor and power abnormal

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

UAInverter

Compressor overcurrent terminal thermal relay operation

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

UEOutdoor

Abnormal high pressure

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

UFInverter

Compressor overcurrent lock

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

ULOutdoor

Abnormal low pressure

Outdoor airflow blockage or dirty condenser coil · Outdoor fan motor or fan driver fault · Refrigerant circuit abnormality or pressure imbalance · Outdoor PCB or protection circuit fault

UPInverter

Compressor overcurrent interruption

Inverter IPM or power module fault · Compressor electrical abnormality or lock · Supply voltage instability or current spike · Heatsink overheating or poor cooling airflow

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Other diagnostic tools

If your unit shows a different symptom or a blinking pattern instead, try a different starting point.

Blinking lights

LED blinking in a pattern? Match it to the likely fault.

Aircon problems

Diagnose a specific symptom like no cooling, water leak, or noise.

Mitsubishi Electric brand hub

Guides, resources, and model info for Mitsubishi Electric aircon.

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