Mitsubishi manufactures high-quality air conditioners for residential and commercial purposes. The company has an extensive range of service centers throughout India.
Usually, Mitsubishi Electric engages authorized third-party service providers for attending to AC installations and troubleshooting. So, users are advised to note the error codes displayed on the remote controller or the IDU when they encounter problems with the Mitsubishi AC. It allows the service technicians to diagnose the faults quickly and accurately, saving considerable time.
Mitsubishi ACs are available in various models. Generally, the error codes vary from one model to the other. Nevertheless, we shall discuss the standard error codes usually observed by residential users.
Mitsubishi AC Error Codes and Fixes
Users should not attempt to repair Mitsubishi AC themselves because the circuits inside the appliance can be complicated. It is advisable to call the authorized Mitsubishi service technician if they encounter any problem with the Mitsubishi AC.
Cleaning the filters is the only activity users should do. We recommend cleaning the AC filters every month to prevent dust accumulation. It affects the appliance’s functioning and also results in higher power consumption.
Here are the standard error codes observed in Mitsubishi ACs
A6 – Communication Error
This error can occur when the AC PCB loses communication with the communication processor. It can be a wiring problem or a loose connection issue. A faulty PCB can also result in a communication error. The AC technician takes appropriate action.
EA – Wiring Issues
The EA error occurs when there is a wiring or a connection issue. For example, the wires could have snapped, or there could be a loose connection problem. As a result, you can experience noise interference. The AC technician checks and repairs the wiring accordingly.
EB – Wiring problems
The EB error is similar to the EA error code. A problem with the wiring or loose interconnecting cables can cause this fault. Though it is an electrical fault, it is advisable to get the AC inspected by an authorized Mitsubishi technician.
EC – Start Up error
The unit does not start after switching on the power. The unit displays the EC error code signifying that the start-up time is over. There can be a timer error. You can try to switch off the unit and restart it. If it does not start, the AC technician is the right person to deal with the problem.
ED – Serial communication error
The error signifies a lack of proper communication between the IDU and ODU or between the IDU and ODU PCBs. The lack of communication in the M-NET system can also cause this error. Users can check whether the ODU PCB connector is disconnected. It can be a wiring issue. The lack of internet connectivity on smart ACs can also cause this error. So, checking the broadband connectivity can resolve the problem.
EF – Non-defined
Some Mitsubishi ACs exhibit the error code EF. It is a non-defined error usually signifying noise interference or lack of power supply to the outdoor unit. In addition, it can be a transmission problem. Usually, switching off the AC and restarting it can resolve the issue. However, if it persists, you must contact the AC technician.
E0, E1, E2, E3, E4, and E5 – Remote controller communication error
All these errors are remote controller issues. Reconnecting the remote controller to the AC power system should resolve the issue. The AC technician must resolve this issue. It can also happen due to the supply of an incompatible remote controller. Changing the remote controller can solve these problems.
E6 – Miscommunication between the indoor and outdoor units
Check the wiring between the IDU and ODU. Try switching the AC off and restarting it. If it does not restart, there could be a snapped connection. The solution is to call the Mitsubishi AC technician and replace the wiring.
E7, E8, and E9 – Communication fault between the IDU and ODU
Improper wiring can cause these errors. Usually, it occurs because of connecting the wires in the wrong sequence. The AC technician should resolve this problem by re-powering the connections correctly.
FA – Installation error, 51CM connector open
Closing the 51CM connector can resolve the problem.
F1 – Installation error, Reverse phase detection.
It is an installation error where the current phases have been misconnected. Reversing the phases can resolve the problem.
F2 – Installation error, L3 phase open
The AC technician should check the power supply and open circuit protection devices.
F3 – Installation error, 63L open
This installation error requires checking the low-pressure switch for loose connections or failure.
F4 – Installation error, 49C open
Checking the inner compressor thermostat for open circuits or contact failure should resolve these problems.
F5 – Installation error, 63H open
The technician should check for the high-pressure switch for contact failure or misconnection.
F7 and F8 – Faulty Outdoor PCB
The solution is to replace the defective PCB. Usually, Mitsubishi offers warranties on the PCB. So, if the unit is under the warranty period, the company replaces it for free.
P1 – Sensor issue, TH1 fault
The P1 error code is the result of the return air thermistor failure. Replacing the sensor is the correct solution.
P2 – Sensor Issue, TH2 fault
The P2 error code signifies a faulty liquid pipe thermistor. The technician should check for disconnection or replace the defective sensor.
P4 – Sensor issue, Drain sensor failure
The P4 error code indicates drain sensor failure. Replace the sensor to rectify the problem.
P5 – Sensor failure, faulty drain pump
The P5 error code indicates a faulty drain pump. So, replacing the defective pump and reconnecting the sensor is the correct solution.
P6 – Reduced airflow
The reason for the reduced airflow can be blockages in the filter or a problem with the fan motor. Users can check the filters and clean them. If the problem persists, there could be a fan motor issue. The AC technician should intervene and check for capacitor failure. Usually, replacing the capacitor resolves the issue.
P8 – Refrigerant leakage issue
The P8 error code requires professional handling. It indicates a refrigerant leakage issue. So, users should not attempt setting it right. The correct solution is to book the service call and summon the technician. The solution is plugging the leakage and refilling the gas.
P9 – Sensor issue, TH5 thermistor open
A loose connection of the condenser or evaporator sensor TH5 can cause the P9 error code. The AC technician reconnects the sensor or replaces it if faulty.
U1 – Outdoor unit fan failure
The U1 error code signifies outdoor unit fan failure. The reason could be a blocked coil or a system blockage. Clogged filters can also cause this error code. The solution is identifying the right problem and resolving it. First, the AC technician inspects the outdoor fan for loose winding coils and capacitor issues. Then, replacing the capacitor and rewinding the fan coils can resolve the issue.
U2 – Overheated compressor
The lack of refrigerant flow can cause the compressor to overheat and display the U2 error code. Check for refrigerant and refill the gas. It should resolve the problem.
U3 – Sensor fault, discharge thermistor failure
A loose connection of the discharge thermistor can cause the U3 error code. The AC technician should reconnect the sensor or replace it.
U4 – Sensor issue, outdoor thermistor failure
An outdoor thermistor failure causes the U4 error code. The solution is to reconnect or replace the sensor.
U5 – Abnormal heat sink temperature
An overheated heat sink can cause the U5 error. The AC technician should check whether the indoor and outdoor units have a short cycle on their air ducts. Measuring the resistance value of the outdoor thermistor TH8 can resolve the issue.
U6 – Abnormal power
Excessive current supply to the compressor causes the error code U6. Check the input current voltage and install a voltage stabilizer to handle such issues.
U7 – Low discharge superheat
The solution is to check for refrigerant levels. A difference in the resistance values among terminals on the indoor and outdoor linear expansion valves can also cause this problem.
U8 – Abnormal outdoor fan speed
A faulty fan capacitor or motor can cause this problem. Technicians can check the TH3 connector on the outdoor controller board. Disconnection or a loose connection can cause this issue.
U9 – Voltage issue
Abnormal input voltage can cause the U9 error code. Users can connect an external voltage stabilizer to rectify the issue. However, the authorized technician should check for other connected matters.
Mitsubishi Numeric Error Codes
Some Mitsubishi AC units display numerical error codes. Most numerical error codes match the alphabetical codes explained above. Nevertheless, we shall list them out for convenience. Almost all errors require the intervention of the authorized Mitsubishi AC technician to resolve the issue.
| Error Code | Fault | Solution |
|---|---|---|
| 0403 | Serial communication error | Check the wiring between the main board and the inverter board. |
| 0900 | Test run | Check Dipswitch SW2-1 on the main control board. |
| 1102 | Discharge temperature fault | Check the compressor’s running current. |
| 1301 | Low-pressure fault | Check the system standing pressure for gas loss |
| 1302 | High-pressure fault | Check for clogged filters or restricted coils. |
| 1500 | Refrigerant overcharge | Check for the excess refrigerant returning to the ODU through overcharging. |
| 2500 | Drain sensor submerge | Check water pump and water flow rate. |
| 2502 | Drain pump fault | Check the float switch for continuity. |
| 2503 | Drain sensor fault | Check for a short circuit and replace the sensor if damaged. |
| 2600 | Water leakage | Check for water leakage on humidifier pipes. |
| 4102 | Open phase | Check power supply, wiring, and fuses. |
| 4106 | Transmission power supply fault | Check wiring, input voltage, and broadband connection. |
| 4115 | Power supply signal sync error | Check mains power, fuses, and PCB connections. |
| 4116 | Motor/RPM error | Check the fan motor connections, confirm secure fixing, clear the debris, or replace the motor/circuit board. |
| 4220 | Abnormal bus voltage | Check mains supply and DC bus voltage. |
| 4225 | Low bus voltage | Check mains power and voltage at the diode stack. |
| 4230 | Heatsink overheat protection | Check for blockages in the air passage, inverter failure, or inverter fan faults. |
| 4240 | Overload protection | Check inverter balance and reduce airflow through the heat sink. |
| 4250 | Over current protection | Check for open and short circuits and repair them. |
| 4255 | Outdoor fan error | Check the voltage on the fan and motor windings for short circuits. |
| 4260 | Heatsink overheat protection at start-up | Replace the THHS thermistor if faulty. |
| 5101 | Temperature sensor fault | Check for fault address code, thermistor connections, and wiring. Otherwise, replace the PCB. |
| 5102 | Return air thermistor fault | Check for connection issues and thermistor resistance and replace the sensors or circuit board. |
| 5110 | Outdoor inverter heatsink thermistor error | Check for open/short circuits and disconnections from the PCB. |
| 5201 | Pressure sensor failure | Reconnect or replace the sensors. |
| 5301 | Current sensor failure | Replace the sensors if faulty. |
| 5701 | Loose float switch connector | Check for correct float switch operations and external pumps. |
| 6201 | Remote controller issue | Replace the remote controller. |
| 6600 | Address overlap | Match the address with the broadband network. |
| 6601 | Polarity setting issue | Check for voltage issues and cable sizes. |
| 6602 | Transmission procedure hardware error | Check the controller and broadband connections, and replace the circuit board if required. |
| 6603 | Transmission line bus busy error | Check for faulty wiring and repair it. |
| 6606 | Communication failure | Check the PCB for defects. Reset the power. If the error persists, replace the PCB. |
| 6607 | No ACK error | Check for power supply, Lossnay address, cable length, and termination. |
| 6608 | No response error | Check and repair cable termination, length, and type of cables used. |
| 6831 | MA controller signal reception error | Check the remote, cable length, types of cable, and connections. |
| 6832 | MA controller comms fault | Check remote, cable length, types of cable used, and connections. |
| 6833 | MA controller comms fault | Same as error code 6832 |
| 6834 | MA controller signal reception error | Same as error code 6832 |
| 7100 | Total capacity error | Add capacities of all indoor units and match them with the outdoor unit capacity. |
| 7101 | Capacity code setting error | Check for capacity dips in IDU and ODU. |
| 7102 | Wrong number of connected units | Check for voltage on the broadband set-top box and if you have connected the correct box. |
| 7105 | Address setting error | Check the address setting on the OC and BC. |
| 7106 | Attribute setting error | Ensure that the SW3-1 setting is on. |
| 7110 | Signal transmission error | Check for broadband connections. |
| 7111 | Remote controller sensor fault | Check SW-1 on the IDU. |
| 7113 | Function setting error | Check the SW5-10 settings and SW6 settings. |
| 7117 | Model setting error | Check the dips, resistors, and thermistors. |
| 7130 | Incompatible unit combination | Check broadband wiring on the systems. |
Final Thoughts
We advise users to contact the Mitsubishi official service center and lodge their complaints online. They should not attempt to repair their ACs by themselves. The authorized technician is the perfect person to handle problems with the AC.
