Mitsubishi Air Conditioner Fault Codes

Here on the page there are lists of error codes for different models of Mitsubishi air conditioners. Mitsubishi fault codes are described separately for each model and accompanied with detailed description of technique behavior and possible causes.

In case if the item has error codes and flashes, the tables contain both of the signals. Several causes are given for every error code. The lists contain also the solutions and recommendations on checking the items. You can solve the situation by changing or repairing a remote control or by checking the wires. If there is any serious repair needed, ask for a specialist’s help.

Mitsubishi Mr. Slim Air Conditioner Fault Codes

Check codeDiagnosis of malfunctionCauseCheck points
EOSignal transmitting/receiving errorDuring individual unit control1) Check the transmission wire.
(Indoor controller does not respond to remote controller signal.)1) Bad contact of transmission wire2) Check with another remote controller. If ■‘EO" is still indicated, replace the indoor controller board.
2) Signal transmitting/receiving circuit is abnormal.If other check code appears, replace the original remote controller.
P1Abnormality of room temperature thermistor (RT1)1) Bad contact of thermistor1) Check the thermistor.
2) Damaged thermistor2) Measure the resistance of the thermistor. Normal resistance should be as follows. 32T-15K2 86°F 4.3ki2
50° F 9.6k£2l04°F 3.0k£2
68°F 6 3ki2
P2Abnormality of indoor coil thermistor (RT2)If the resistance is normal, replace the indoor controller board.
P3Signal transmission error (Remote controller does not respond to indoor controller signal.)1) Bad contact of transmission wire1) Check the transmission wire.
2) Signal transmitting/receiving circuit is abnormal.2) Check with another remote controller.
3) Wrong operation due to noise wave emitted by other appliancesIf “P3’ is still indicated, replace the indoor board.
If other check code appears, replace the original remote controller.
3) Short-circuit between D and (2) of CN40 and attach CN40 to the following units.
• Second unit in twin control
• Second and third units in triple control
• Sub units in group control
P4Abnormality of drain sensor1) Bad contact of transmission wire1) Check the connector.
2) Damaged thermistor2) Measure the resistance of the thermistor As for the normal resistance, refer to the case of P1.
If the resistance is normal, replace the indoor controller board.
P5Malfunction of drain pump1) Malfunction of drain pump1) Check the drain pump.
2) Damaged drain sensor2) • Check the drain sensor.
• Check the drain sensor heater. Normal resistance should be 8212.
If the resistance is normal, replace the indoor controller board.
P6Coil frost protection is working.1) Short cycle of air cycle1) Clear obstructions from the air cycle.
2) Dirty air filter2) Clean the air filter
3) Damaged fan3) Check the fan.
4) Abnormal refngerant4) Check the refrigerant temperature.
P7System error1) Wrong address-setting1) Check the address-setting.
2) Signal transmitting/receiving circuit of remote controller is abnormal.2) Check with another remote controller. If check code other than “P7” appears, replace the original remote controller.
3) Wrong SW6-setting3) Check SW6 setting.
P8Abnormality in outdoor unit1) Wrong wiring of indoor/outdoor connecting wire1) Check the indoor/outdoor connecting wire.
2) Reversed phase2) Change the connection of electric wiring.
3) Protection device is working3) Check the protection device.
4) Damaged outdoor coil thermistor4) Measure the resistance of the outdoor coil thermistor. If the resistance is normal, replace the outdoor controller board.

Mitsubishi Mr Slim P Series Air Conditioner Fault Codes

Indoor unit indicator RUN lightIndoor unit indicator TIMER lightOutdoor unit Indicator LEDWired remote Controller display (optional part)Description of trouble
Come s ON1 time flash1 time flashE42Current cut• Compressor locking
• Open phase on compressor output
• Short circuit on power transistor
Come s ON2 time flash2 time flashE59Trouble of outdoor unit• Defective power transistor
• Broken compressor wire
• Compressor blockage
Come s ON3 time flash3 time flashE58Current safe stop• Overload operation
• Overcharged
Come s ON4 time flash4 time flashE41Power transistor error• Broken power transistor
Come s ON5 time flash5 time flashE36Over heat of compressor• Gas shortage
• Defective discharge pipe sensor
Come s ON6 time flash6 time flashE5Error of signal transmission• Defective power supply
• Broken signal wire
• Defective indoor/outdoor PCB
Come s ON7 time flashComes ONE48Outdoor fan motor error• Defective fan motor
• Poor connector connection
2 time flash2 time flash7 time flashElError of wired remote controller wiring• Broken remote control wire
• Defective indoor unit PCB

Mitsubishi PWFY Air Conditioner Fault Codes

FAULT CODEI DESCRIPTION
E1Faulty controller
E3Transmitting Error (PAR W21) - check refrigerant address on SW1 of Ecodan
E4Receiving Error (PAR W21) - check refrigerant address of SW1 on Ecodan
E5Receiving Error (PAR W21) - check refrigerant address of SW1 on Ecodan
E6Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
E8Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
E9Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
EFNon-defined error code - noise interference - power down Ecodan for 30 seconds then switch back on
EDSerial communication fault between Ecodan main board and Ecodan inverter board - mainly due to loose CN2 or CN5 cable
P1Flow temp sensor fault - TH1 not connected, short or open circuit
P6Over heating at heat exchanger - lack of water flow, air in the system, flow rate incorrectly set, blockage or pump problem

Mitsubishi CAHV Air Conditioner Fault Codes

CodeSymptom
P1Intake sensor error
P2, P9Pipe (Liquid or 2-phase pipe) sensor error
E6, E7Indoor/outdoor unit communication error
P4Drain sensor error
P5Drain pump error
PAForced compressor error
P6Freezing/Overheating safeguard operation
EECommunication error between indoor and outdoor units
P8Pipe temperature error
E4Remote controller signal receiving error
FbIndoor unit control system error (memory error, etc.)
EO, E3Remote controller transmission error
E1, E2Remote controller control board error
E9Indoor/outdoor unit communication error (Transmitting error) (Outdoor unit)
UPCompressor overcurrent interruption
U3, U4Open/short of outdoor unit thermistors
UFCompressor overcurrent interruption (When compressor locked)
U2Abnormal high discharging temperature/49C worked/insufficient refrigerant
U1, UdAbnormal high pressure (63H worked)/Overheating safeguard operation
U5Abnormal temperature of heat sink
U8Outdoor unit fan safeguard stop
U6Compressor overcurrent interruption/Abnormal of power module
U7Abnormality of super heat due to low discharge temperature
U9, UHAbnormality such as overvoltage or voltage shortage and abnormal synchronous signal to main circuit/ Current sensor error

Mitsubishi Ecodan Air Conditioner Fault Codes

Indoor unit indicator RUN lightIndoor unit indicator TIMER lightOutdoor unit Indicator LEDWired remote Controller display (optional part)Description of Trouble
1 time flashComes ONStays OFFE6Indoor heat exchanger sensor 1 error• Broken heat exchanger sensor 1 wire,
• Poor connector connection
2 time flashComes ONStays OFFE 7Room temperature sensor error• Broken room temperature sensor wire,
• Poor connector connection
4 time flashComes ONStays OFFE9Drain abnormal (STM. SRRM only)• Float switch defective,
• Reverse gradient on drain
5 time flashComes ONStays OFFE6Indoor heat exchanger Sensor 2 error• Broken heat exchanger sensor 2 wire,
• Poor connector connection
6 time flashComes ONStays OFFEl 6Indoor fan motor error• Defective fan motor,
• poor connector connection
7 time flashComes ONStays OFFE6Refrigerant insufficient Closed service valve Heat exchanger sensor 1 error• Refrigerant is insufficient, leaking
• Closed service valve
• Heat exchanger sensor 1 wire,
• poor connector connection
Keeps1 time flashKeeps flashingE38Outdoor air temperature sensor error• Broken outdoor sensor wire,
flashing• poor connector connection
Keeps2 time flashKeeps flashingE37Outdoor heat exchanger sensor error• Broken heat exchanger fluid pipe sensor wire,
flashing• poor connector connection
Keeps4 time flashON 4 sec OFF 4 secE39Discharge pipe sensor error• Broken discharge pipe sensor wire,
flashing• poor connector connection
Keeps5 time flashKeeps flashingE53Suction pipe sensor error• Broken suction pipe sensor wire,
flashing• poor connector connection
Keeps6 time flashKeeps flashingE41Power transistor sensor error• Broken power transistor sensor wire,
flashing• poor connector connection

Mitsubishi City Multi Air Conditioner Fault Codes

FAULT CODEDESCRIPTION
F3Low pressure switch failure - check connection on the board and continuity of switch
F5High pressure switch failure - check connection onto board and continuity of switch
F9Both pressure switch contacts are open at the same time - check connection onto board and continuity of switch and for a potential board failure
EAMis-wiring fault between FTC and Ecodan - check S1 ,S2,S3 also check voltages and comms
EBMis-wiring fault between FTC and Ecodan - Check S1 ,S2,S3 also check voltages and comms
ECUnit cannot finish start up process - generally caused by a comms fault
U1Ecodan high pressure fault - mainly caused by incorrect water flow rates - check with flow setter
U2Ecodan high compressor discharge temperature - mainly caused by refrigerant shortage or dirty condenser
U3Ecodan discharge thermistor problem - mainly caused by TH4 discharge thermistor - open/close circuit
U4Open or close circuit Ecodan thermistors (TH3, TH32, TH33, TH6, TH7, TH8) - open or close circuit or disconnected from main board

Mitsubishi Mr.Slim A Air Conditioner Fault Codes

FAULT CODELED 1LED 2I DESCRIPTION
AO2 flash5 flashDuplicate address - Lossnay units attached with the same address -
change addresses and reset the units power
A22 flash5 flashHardware error of transmission processor (Lossnay) - check comms wiring,
and for possible Lossnay board fault
A32 flash5 flashLine busy no data could be transmitted for 8 minutes - check A- M-Net
connections (TB7 and TB3)
A62 flash5 flashCommunication error with communication processor - Lossnay address not
transmitted - check M-Net voltage
A72 flash5 flashNo ACK signal - check A- M-Net wiring, range of transmission wiring exceeded
or if faulty A- M-Net converter
A82 flash5 flashM-Net no response - check A- M-Net wiring, range of transmission wiring
exceeded, faulty A- M-Net converter or if incorrect wire used for M-Net connection
EA--Mis-wiring/loose inter-connecting cables. Noise interference.
EB--Mis-wiring/loose interconnecting cables. Noise interference. Wrong cable size/spec
ECStart-up time over. The unit has failed to initialise after power up.
Noise interference. Wrong cable size/spec.
ED2 flash5 flashSerial communication error. Comms error between boards on outdoor unit
caused by M-Net interface board incorrectly fitted.
EF2 flash4 flashNon-defined error code. Noise interference - power down outdoor unit for 30 seconds
then switch back on
EO2 flash3 flashRemote controller communication error - check wiring, connections and comms
voltage. Also check Master/Slave settings if multiple systems are connected
E1--Remote controller issue - if grouped, check addressing. If twinned, check
wired to master indoor only
E2--Remote controller issue - if grouped, check addressing. If twinned, check
wired to master indoor only
E32 flash3 flashRemote controller issue - not transmitting - if grouped, check addressing.
If twinned check wired to master indoor only
E42 flash3 flashRemote controller issue - not receiving - if grouped, check addressing.
If twinned, check wired to master indoor only
E52 flash3 flashRemote controller issue - not receiving - if grouped, check addressing.
If twinned, check wired to master indoor only

Mitsubishi MR. SLIM MSY-A24NA Air Conditioner Fault Codes

FlashingRUN lightDescription of troubleCause
TIMER light ON1 Time flashHeat exchanger sensor 1 error• Broken heat exchanger sensor 1 wire, poor connector connection
2 Time flashRoom temperature sensor error• Broken room temperature sensor wire, poor connector connection
3 Time flashHeat exchanger sensor 3 error• Broken heat exchanger sensor 3 wire, poor connector connection
5 Time flashActive filter voltage error• Defective power supply
6 Time flashIndoor fan motor error• Defective fan motor, poor connector connection
7 Time flashRefrigerant insufficient• Refrigerant is insufficient, leaking
Closed service valve• Closed service valve
Heat exchanger sensor 1 error• Heat exchanger sensor 1 wire, poor connector connection
RUN light Keeps flashing1 Time flashOutdoor temperature sensor errorBroken outdoor sensor wire, poor connector connection
2 Time flashOutdoor heat exchanger fluid pipe Sensor errorBroken heat exchanger fluid pipe sensor wire, poor connector connection
3 Time flashDischarge pipe sensor errorBroken discharge pipe sensor wire, poor connector connection
5 Time flashSuction pipe sensor errorBroken suction pipe sensor wire, poor connector connection