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Mitsubishi Troubleshooting

List of Mitsubishi Aircon Error Codes

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Knowing how to spot and understand a Mitsubishi error code is a critical step in fixing common issues that usually affect the brand’s lineup of aircons. Since Mitsubishi AC units are equipped with an advanced self-diagnostics system, owners are always notified when something’s wrong with the machine.


But in order to get to the cause of the problem, you will need to familiarize yourself with the brand’s long list of error codes. In this guide, we’ll show you the complete Mitsubishi aircon error codes and what they usually mean for your unit.


Mitsubishi AC Error Codes

Code Possible Cause
P1 Intake sensor error
P2 P9 Pipe (Liquid or 2-phase pipe) sensor error
E6 E7 Indoor/outdoor unit communication error
P4 Drain sensor error
P5 Drain pump error
PA Forced compressor error
P6 Freezing/Overheating safeguard operation
EE Communication error between indoor and outdoor units
P8 Pipe temperature error
E4 Remote controller signal receiving error
Fb Indoor unit control system error (memory error, etc.)
E0 E3 Remote controller transmission error
E1 E2 Remote controller control board error
E9 Indoor/outdoor unit communication error (Transmitting error) (Outdoor unit)
UP Compressor overcurrent interruption
U3, U4 Open/short of outdoor unit thermistors
UF Compressor overcurrent interruption (When compressor locked)
U2 Abnormal high discharging temperature/49C worked/insufficient refrigerant
U1 Ud Abnormal high pressure (63H worked)/Overheating safeguard operation
U5 Abnormal temperature of heat sink
U8 Outdoor unit fan safeguard stop
U6 Compressor overcurrent interruption/Abnormal of power module
U7 Abnormality of superheat due to low discharge temperature
U9 UH Abnormality such as overvoltage or voltage shortage and abnormal synchronous signal to main circuit/ Current sensor error.

Mitsubishi Mr. Slim A-control Error Codes

Code Possible Cause
EA Error detail Miswiring of indoor/outdoor unit. exceed the number of indoor unit connection.
EB Error detail Miswiring of indoor/outdoor unit. (mis-wiring disconnection)
EC Error detail Start-up time over
E6 Error detail Indoor/outdoor unit transmission error (signal receiving error)
E7 Error detail Indoor/outdoor unit transmission error (transmitting error)
E8 Error detail Indoor/outdoor unit transmission error (signal receiving error)
E9 Error detail Indoor/outdoor unit transmission error (transmitting error)
E0 Error detail Remote control transmission error (signal receiving error)
E3 Error detail Remote control transmission error (transmitting error)
E4 Error detail Remote control transmission error (signal receiving error)
E5 Error detail Remote control transmission error (transmitting error)
EF Error detail M-NET transmission error
ED Error detail Serial transmission error
P1 Error detail Abnormality of room temperature thermistor (TH1)
P2 Error detail Abnormality of pipe temperature thermistor/liquid (TH2)
P4 Error detail Abnormality of drain sensor (DS)
P5 Error detail Malfunction of drain-up machine
P6 Error detail Freezing/overheating protection detect
P8 Error detail Abnormality of pipe temperature
P9 Error detail Anormality of pipe temperature thermistor/condenser/evaporator (TH5)
F1 Error detail Reverse phase detection
F2 Error detail L3 open phase detection
F3 Error detail 63L connector open
F4 Error detail 49C connector open
F9 Error detail Connector 2 or more open
FA Error detail L2-phased open phase or 51CM connector open
F7 Error detail Reverse phase detection circuit (p.c.board) fault
F8 Error detail Input circuit fault
U2 Error detail Abnormal high discharging temperature
U2 Error detail Inner thermostat (49C) operation
U1 Error detail Abnormal high pressure (high pressure swicth 63H worked)
U1 Error detail Direct cut operation
UE Error detail High pressure error (ball valve closed)
UL Error detail Abnormal low pressure
UD Error detail Overheat protection
U6 Error detail Compressor over current (overload) cut off
UA Error detail Compressor over current (terminal relay operation)
UF Error detail Compressor over current (start-up locked) cut off
UF Error detail Compressor over current (operating locked) cut off
UH Error detail Current sensor error
U3 Error detail Discharge thermistor short/open
U4 Error detail Outdoor thermistor short/open
Mr.Slim K-control Display of remote controller
LED E0 Diagnosis of malfunction Transmitting/receiving signal error
LED P1 Diagnosis of malfunction Intake air sensor abnormal
LED P2 Diagnosis of malfunction Pipe sensor abnormal
LED P4 Diagnosis of malfunction Drain sensor abnormal
LED P5 Diagnosis of malfunction Malfunctioning of the drain overflow protecting mechanism
LED P6 Diagnosis of malfunction Abnormality of the coil frost/overheating protection mode
LED P3 Diagnosis of malfunction System error (transmitting/receiving signal)
LED P7 Diagnosis of malfunction System error (address)
LED P8 Diagnosis of malfunction Outdoor unit malfunction
Mr.Slim K-control PUH-EK Outdoor unit
LED ON Operation status
LED Flash Check code display
LED LD1 LED ON Compressor directive
LED Flash Reverse phase detect
LED LD2 LED ON Heating directive
LED Flash Open phase detect
LED LD3 LED ON During 63H1 operation
LED Flash Pipe sensor short/open
LED LD4 LED ON Compressor ON
LED Flash High pressure switch (63H2) operation
LED LD5 LED ON Outdoor fan ON
LED Flash Over current relay (51CM) operation
LED LD6 LED ON 4-way valve ON
LED Flash Thermal switch (26C) operation
LED LD7 LED ON Bypass valve ON
LED Flash Thermistor (TH3) overheat protection
LED LD8 LED ON Crankcase heater ON
LED Flash Defective input

Mitsubishi Mr. Slim Error Codes (Membrane Type Remote Controllers)

Code Possible Cause
EO During individual unit control:
Bad contact of transmission wire
Signal transmitting/receiving circuits are abnormal
P1 Bad contact of thermistor
Damaged thermistor
P2 Bad contact of thermistor
Damaged thermistor
P3 Bad contact of transmission wire
Signal transmitting/receiving circuits are abnormal
Wrong operation due to noise wave emitted by other appliances
P4 Bad contact of transmission wire
Damaged thermistor
P5 Malfunction of drain pump
Damaged drain sensor
P6 Short cycle of air cycle
Dirty air filter
Damaged fan
Abnormal refrigerant
P7 Wrong address-setting
Signal transmitting/receiving circuit of remote controller is abnormal
Wrong SW6-setting
P8 Wrong wiring of indoor/outdoor connecting wire
Reversed phase
Protection device is working
Damaged outdoor coil thermistor

Also read: Daikin Error Codes (Indoor, Outdoor and System)

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