Understanding the common error codes associated with Mitsubishi split AC units is essential for maintaining their performance and longevity. Just like any electronic device, Mitsubishi split air conditioners can experience various errors and malfunctions that can hinder their efficiency. These issues may range from simple fixable problems to more intricate faults that necessitate professional intervention.

To ensure your Mitsubishi split AC operates smoothly, it’s critical to recognize and address these error codes promptly. In this blog post, we will review the top ten error codes specific to Mitsubishi split AC units and provide you with practical solutions for each one. By familiarizing yourself with these error codes and their fixes, you can help your Mitsubishi split AC continue to perform at its best.

Let’s explore the most common error codes found in Mitsubishi split AC units and learn how to troubleshoot them effectively.

Mitsubishi Split AC Error Codes

Mitsubishi 4-Digit Error Codes

  • 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 AC Error Codes

  • 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

  • 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 switch 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 Error Codes

  • 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.

Top 10 Mitsubishi Split AC Error Codes Lits

Here are the top 10 Mitsubishi Split AC error codes, along with their explanations and possible solutions:

E0 – Remote controller communication error:

This error occurs when a communication problem occurs between the indoor unit and the remote controller.

Solution: Check the batteries in the remote controller and replace them if necessary.

Ensure no obstacles block the signal between the remote controller and the indoor unit.

E1 – Indoor/outdoor unit communication error:

This error indicates a communication problem between the indoor and outdoor units.

Solution: Check the wiring connections between the indoor and outdoor units. Make sure they are properly connected and not damaged.

If the problem persists, consult a professional technician.

E2 – Zero-cross signal error:

This error occurs when the zero-cross signal is not detected.

Solution: Contact a qualified technician to diagnose and resolve the issue. It may require repairing or replacing certain electrical components.

E3 – Fan speed malfunction:

This error indicates a problem with the fan speed.

Solution: Check the fan motor and its wiring connections. Clean the fan blades and ensure that they are not obstructed.

If the issue persists, contact a professional technician for assistance.

E4 – Outdoor unit temperature sensor error:

This error occurs when there is a problem with the outdoor unit’s temperature sensor.

Solution: Inspect the outdoor unit’s temperature sensor for any damage or loose connections.

Replace the sensor if necessary. If the problem persists, seek professional help.

E5 – Overcurrent protection error:

This error indicates an overcurrent protection activation.

Solution: Check the power supply and electrical connections. Ensure that the current rating is appropriate for the AC unit.

If the issue persists, contact a professional technician to investigate and resolve the problem.

E6 – Communication error between indoor unit and fan motor:

This error occurs when there is a communication problem between the indoor unit and the fan motor.

Solution: Inspect the wiring connections between the indoor unit and the fan motor.

Check for any loose or damaged connections. If necessary, consult a professional technician to fix the issue.

E7 – Outdoor unit fan motor malfunction:

This error indicates a problem with the outdoor unit’s fan motor.

Solution: Inspect the outdoor unit’s fan motor and its wiring connections.

Clean the fan blades and ensure that they are not obstructed. If the issue persists, seek professional help.

E8 – Water level alarm:

This error occurs when the water level in the drain pan is too high.

Solution: Check the drain pan and remove any accumulated water. Inspect the drain pipe for blockages and clear them if necessary.

Ensure that the unit is installed properly to allow proper drainage.

E9 – High-pressure protection error:

This error indicates that the high-pressure protection has been activated.

Solution: Check the outdoor unit for any blockages or obstructions that may be causing high pressure.

Clean the condenser coils and ensure proper airflow. If the issue persists, consult a professional technician to diagnose and resolve the problem.

It’s important to note that these error codes may vary slightly depending on the specific model and version of your Mitsubishi Split AC.

Always refer to the user manual or contact Mitsubishi customer support for accurate information and assistance.

Mitsubishi error code

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Ralph P. Sita
Author: Ralph P. Sita

Ralph P. Sita is a seasoned professional with deep roots in both the HVAC and tech industries. His family’s business, Ralph P. Sita, Inc., is a locally owned and operated HVAC contractor with over 42 years of experience, serving the DC, Maryland, and Virginia areas. The company specializes in residential, commercial, and industrial heating, ventilation, and air conditioning services, offering everything from installation and maintenance to custom ductwork and indoor air quality solutions -www.ralphpsita.com. A former CPA, he spent the last decade as co-founder and co-CEO at Cybrary, a leading platform for cybersecurity and IT training. Cybrary became the largest, most well-known cybersecurity training businesses in the industry under his leadership. Smart AC Solutions is an opportunity to give back to the HVAC community by providing reliable, actionable information on all things heating and cooling.

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Ralph P. Sita is a seasoned professional with deep roots in both the HVAC and tech industries. His family’s business, Ralph P. Sita, Inc., is a locally owned and operated HVAC contractor with over 42 years of experience, serving the DC, Maryland, and Virginia areas. The company specializes in residential, commercial, and industrial heating, ventilation, and air conditioning services, offering everything from installation and maintenance to custom ductwork and indoor air quality solutions -www.ralphpsita.com.

A former CPA, he spent the last decade as co-founder and co-CEO at Cybrary, a leading platform for cybersecurity and IT training. Cybrary became the largest, most well-known cybersecurity training businesses in the industry under his leadership.

Smart AC Solutions is an opportunity to give back to the HVAC community by providing reliable, actionable information on all things heating and cooling.