Mitsubishi Air Conditioner Error Codes

Air conditioner manufacturers, including Mitsubishi, often include error codes in their manuals for user reference. If you no longer have the manual for your unit, check our list below for the list of Mitsubishi error codes by unit model. Mitsubishi Error Code Lookup

Mitsubishi 4-Digit Error Codes

Error Code Number	Air Conditioner Fault Description
0403	Serial communication error
0900	Test run
1102	Discharge temperature fault
1301	Low pressure fault
1302	High pressure fault
1500	Refrigerant overcharge
2500	Drain sensor submergence
2502	Drain pump fault
2503	Drain sensor fault
2600	Water leak
4102	Open phase
4106	Transmission power supply fault
4115	Power supply signal sync error
4116	RPM error/Motor error
4220	Abnormal bus voltage
4225	Low bus voltage
4230/4260	Heatsink overheat protection activated
4240	Overload protection activated
4250	Overcurrent protection activated
4255	Outdoor unit fan error
5101	Temperature sensor fault
5102	Return air thermistor fault
5110	Outdoor unit inverter heatsink thermistor error
5201	Pressure sensor fault
5301	Current sensor fault
5701	Loose float switch
6201	Remote controller issue
6600	Address overlap
6601	Polarity setting error
6602	Transmission processor hardware error
6603	Transmission line busy
6606	Communication fault
6607	No ACK
6608	No response
6831/6834	MA controller signal reception error
6832/6833	MA controller comms fault
7100	Total capacity error
7101	Capacity code setting error
7102	Wrong number of connected units
7105	Address setting error
7106	Attribute setting error
7110	Signal transmission error
7111	Remote controller sensor fault
7113	Function setting error
7117	Model setting error
7130	Incompatible unit combination

Mitsubishi Electric Air Conditioner Error Codes

Error Code Number and Letter	Air Conditioner Fault Description
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
U6	Compressor overcurrent interruption/Abnormal of power module
U7	Abnormality of superheat due to low discharge temperature
U8	Outdoor unit fan safeguard stop
U9	UH Abnormality such as overvoltage or voltage shortage and abnormal synchronous signal to the main circuit/ Current sensor error.

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Mitsubishi Mr. Slim-A Control Error Codes

• A0: Duplicate address; Lossnay units attached using the same address
• A2: Hardware error transmission processor
• A3: No data transmission for 8 minutes due to busy line
• A6: Communication error with processor; Lossnay address not being transmitted
• A7: No ACK signal
• A8: No M-Net response
• E0: Remote control transmission error (signal receiving error)
• E0-E5: Signal error between remote control and indoor units
• E1: Remote control communication issue
• E2: Remote control transmission error
• E3: Remote control transmission error (transmitting error)
• E3/E5: Remote control communication/receiving error
• E4: Remote control transmission error (signal receiving error)
• E5: Remote control transmission error (transmitting error)
• E6: Indoor and outdoor unit communication error
• E6-EF: Communication error between indoor and outdoor units
• E7: Indoor and outdoor unit communication error
• E8: Indoor and outdoor unit communication error
• E9: Indoor and outdoor unit communication error
• EA: Miswiring of indoor/outdoor unit (Exceeded the number of indoor unit connections)
• EB: Miswiring of indoor/outdoor unit (Miswiring disconnection)
• EC: Start-up time over
• ED: Serial communication error between boards on outdoor unit due to incorrectly fitted M-Net interface board
• EF: M-NET transmission error
• Ed: Serial transmission error
• F1: Reverse phase detection
• F1-FA: Outdoor unit error
• F2: L3 open phase detection
• F3: 63L connector open
• F4: 49C connector open
• F5: 63H connector open
• F7: Reverse phase detection circuit (P.C. board) fault
• F8: Input circuit fault
• F9: Connector 2 or more open
• FA: L2-phased open phase or 51CM connector open
• LED E0: Diagnosis of malfunction Transmitting / Receiving signal error
• 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
• LED ON: Operation status
• LED P1: Intake air sensor abnormal
• LED P2: Pipe sensor abnormal
• LED P3: System error (transmitting/receiving signal)
• LED P4: Drain sensor abnormal
• LED P5: Malfunctioning of the drain overflow protecting mechanism
• LED P6: Abnormality of the coil frost / overheating protection mode
• LED P7: System error (address)
• LED P8: Outdoor unit malfunction

Mr.Slim K-control: PUH-EK Outdoor unit

• P1: Abnormality of room temperature thermistor (TH1)
• P2: Abnormality of pipe temperature thermistor/liquid (TH2)
• P4: Abnormality of drain sensor (DS)
• P5: Malfunction of drain-up machine
• P6: Freezing/overheating protection detect
• P8: Abnormality of pipe temperature
• P9: Abnormality of pipe temperature thermistor/condenser/evaporator (TH5)
• U0-UP: Outdoor unit error
• U1: Direct cut operation
• U2: Inner thermostat (49C) operation
• U3: Discharge thermistor short/open
• U4: Outdoor thermistor short/open
• U5: Inverter heat sink overheating
• U6: Compressor over current
• U7: Low discharge superheat (TH4)
• UA: Compressor overcurrent (terminal relay operation)
• UE: High pressure error (ball valve closed)
• UF: Compressor overcurrent (operating locked) cut off
• UH: Current sensor error
• UL: Abnormal low pressure
• Ud: Overheat protection

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

Check code	Diagnosis of malfunction	Cause	Check points
EO	Signal transmitting/receiving error (Indoor controller does not respond to remote controller signal.)	During individual unit control 1) Bad contact of transmission wire 2) Signal transmitting/receiving cir- cuit is abnormal.	1) Check the transmission wire. 2) Check with another remote controller. If “EO” is still indicated, replace the indoor controller board. If other check code appears. replace the origi-nal remote controller.
P1 P2	Abnormality of room temper- ature thermistor (RT1) Abnormality of indoor coil thermistor (RT2)	1) Bad contact of thermistor 2) Damaged thermistor	1) Check the thermistor. 2) Measure the resistance of the thermistor. Normal resistance should be as follows. 32°F····15kΩ 86°F·····4.3kΩ 50°F······9.6kΩ104°F·····3.0kΩ 68°F······6.3kΩ If the resistance is normal, replace the indoor controller board.
P3	Signal transmission error (Remote controller does not respond to indoor controller signal.)	1) Bad contact of transmission wire 2) Signal transmitting/receiving cir- cuit is abnormal. 3) Wrong operation due to noise wave emitted by other appli- ances	1) Check the transmission wire. 2) Check with another remote controller. If “P3” is still indicated, replace the indoor board. If other check code appears, replace the origi- nal remote controller. 3) Short-circuit between ¬ and Á of CN40 and attach CN40 to the following units. l Second unit in twin control l Second and third units in triple control l Sub units in group control
P4	Abnormality of drain sensor	1) Bad contact of transmission wire 2) Damaged thermistor	1) Check the connector. 2) Measure the resistance of the thermistor à – Ä. As for the normal resistance, refer to the case of P1. If the resistance is normal, replace the indoor con- troller board.
P5	Malfunction of drain pump	1) Malfunction of drain pump 2) Damaged drain sensor	1) Check the indoor/outdoor connecting wire. 2) Change the connection of electric wiring. 3) Check the protection device. 4) Measure the resistance of the outdoor coil ther- mistor. If the resistance is normal, replace the outdoor controller board.
P6	Coil frost protection is work- ing.	1) Short cycle of air cycle 2) Dirty air filter 3) Damaged fan 4) Abnormal refrigerant	1) Clear obstructions from the air cycle. 2) Clean the air filter 3) Check the fan. 4) Check the refrigerant temperature.
P7	System error	1) Wrong address-setting 2) Signal transmitting/receiving cir- cuit of remote controller is abnormal. 3) Wrong SW6-setting	1) Check the address-setting. 2) Check with another remote controller. If check code other than “P7” appears, replace the origi- nal remote controller. 3) Check SW6 setting.
P8	Abnormality in outdoor unit	1) Wrong wiring of indoor/outdoor connecting wire 2) Reversed phase 3) Protection device is working 4) Damaged outdoor coil thermis- tor	1) Check the indoor/outdoor connecting wire. 2) Change the connection of electric wiring. 3) Check the protection device. 4) Measure the resistance of the outdoor coil ther- mistor. If the resistance is normal, replace the outdoor controller board.