E0/E3Communication
Remote controller transmission error
Typical causes
- Loose or damaged interconnection or controller wiring
- Poor terminal contact or connector corrosion
- Indoor or outdoor PCB communication circuit fault
- Power supply instability
Mitsubishi Electric Aircon Error Codes
Reference table for common Mitsubishi Electric codes. Use it to understand likely meaning, typical causes, and context before booking.
Before you use this tool
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.
Mitsubishi Electric code table
Includes common SG residential split-system codes with likely meaning and typical causes.
E1Communication
Wired remote controller communication fault
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
E38Sensor
Outdoor heat exchanger sensor fault
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
E39Sensor
Outdoor discharge pipe sensor fault
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
E40Outdoor
Heating high pressure protection
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
FBIndoor
Indoor control system error
Typical causes
- 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
Typical causes
- 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
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
P2/P9Sensor
Indoor pipe thermistor abnormal
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
P4Sensor
Drain sensor abnormal
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
U4Sensor
Outdoor thermistor open or short
Typical causes
- Thermistor or sensor open or short circuit
- Loose sensor connector or damaged harness
- Control PCB sensor input fault
U5Sensor
Inverter heatsink temperature abnormal
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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
Typical causes
- 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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