Mitsubishi Mini-Split Error Codes: Complete Diagnostic List
20 diagnostic codes documented · Official site ↗
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Indoor/Outdoor Mismatch
Mitsubishi's error code 1 indicates that the indoor and outdoor units are not communicating properly. This could be due to a faulty communication wire, a problem with the control board, or an issue with the remote control. The system is designed to prevent damage by displaying this error and shutting down. However, it's important to resolve the issue to restore full functionality.
Power Supply Phase Error
A Power Supply Phase Error (Error Code 2) on your Mitsubishi HVAC system indicates that the unit has detected an issue with the incoming power supply. This could be due to a voltage fluctuation, a phase issue, or a problem with the power supply itself. The system is designed to protect itself from potential damage by displaying this error and shutting down certain functions. It's important to have this checked by a professional to ensure safe and efficient operation of your HVAC system.
Communication Error
A communication error (error code 3) on your Mitsubishi HVAC system means that the indoor and outdoor units are not communicating properly with each other. This can happen due to a variety of reasons, such as a faulty communication wire, a problem with the control board, or an issue with the remote control. When this error occurs, your system may not function as intended, and you might notice that it's not heating or cooling your space effectively.
Inverter Error
The Mitsubishi 4 error indicates a problem with your system's inverter, which controls the speed of the compressor. This error can be caused by a variety of issues, but it's important to note that it's not an immediate safety hazard. However, it's crucial to address this issue promptly to prevent further damage to your system.
Outdoor Thermistor Open/Short
The Mitsubishi 5 error, also known as an 'Outdoor Thermistor Open/Short', indicates that your system has detected an issue with the outdoor thermistor. This component is responsible for measuring the temperature outside your home and communicating this information to your HVAC system. If the system detects that the thermistor is not functioning properly, it will shut down to prevent further damage. This error is typically caused by a faulty thermistor, but it could also be due to a problem with the wiring or the control board.
Indoor Freeze/Overheat
Mitsubishi's error code 6 indicates that your indoor unit's temperature has either dropped too low (freeze) or risen too high (overheat). This could be due to airflow obstruction, refrigerant issues, or a faulty temperature sensor. The system will continue to operate, but with reduced performance to prevent further damage.
Outdoor Freeze/Overheat
Mitsubishi's error code 7 indicates that the outdoor unit has either frozen or overheated. This is a safety feature designed to protect your system from potential damage. The most common causes for this error are dirty or frozen evaporator coils, low refrigerant levels, or a faulty temperature sensor. Less common causes include issues with the defrost control board or the outdoor fan motor.
Indoor/Outdoor Communication Error
The E6 error on your Mitsubishi HVAC system indicates a communication issue between the indoor and outdoor units. This could be due to a faulty communication wire, a problem with the control board, or an issue with the outdoor unit's fan. The system will continue to operate, but some features may be limited.
Indoor/Outdoor Communication Fault
The E9 error on your Mitsubishi HVAC system indicates a communication fault between the indoor and outdoor units. This could be due to a broken wire, a faulty control board, or an issue with the communication cable. The system will continue to operate, but you may notice reduced performance or comfort. It's important to address this issue promptly to prevent further damage or system failure.
Intake Sensor Error
The P1 error code on your Mitsubishi HVAC system indicates a problem with the intake sensor. This sensor measures the temperature and pressure of the air entering your system. If it's not working properly, your system may not function as efficiently as it should. While this isn't an immediate safety hazard, it's important to address the issue to prevent further damage or higher energy bills.
Indoor Pipe Thermistor Error
The P2 error code on your Mitsubishi HVAC system indicates a problem with the indoor pipe thermistor. This component measures the temperature of the refrigerant as it enters the indoor unit. If it's not working properly, your system might not cool or heat correctly. The most common causes are a faulty thermistor or a problem with the wiring.
Drain Sensor Error
The P4 error code on your Mitsubishi HVAC system indicates a fault with the drain sensor. This sensor is responsible for detecting water buildup in the condensate pan. When it malfunctions, it can cause your system to shut down to prevent water damage. The most common causes for this error are a clogged drain line or a faulty sensor.
Drain Pump Error
The P5 error on your Mitsubishi HVAC system indicates that the drain pump, responsible for removing condensed water, is not functioning correctly. This could be due to a clogged drain line, a faulty pump, or an issue with the float switch that senses water levels. The system will continue to operate, but water may back up and cause damage or reduce cooling efficiency. It's important to address this issue promptly to prevent potential water damage or reduced comfort.
Coil Freeze/Overheat Protection
The P6 error code on your Mitsubishi HVAC system indicates that the coil freeze/overheat protection feature has been activated. This could be due to a blockage in the airflow, a refrigerant leak, or a malfunctioning sensor. The system has temporarily shut down to prevent further damage. It's important to address this issue promptly to avoid potential system failure.
Pipe Temp Error
The P8 error on your Mitsubishi HVAC system indicates that the pipe temperature has exceeded the safe operating range. This could be due to a faulty temperature sensor or a problem with the system's refrigerant flow. If left unchecked, this issue can lead to system damage and reduced efficiency.
High Pressure Trip
The U1 error code on your Mitsubishi HVAC system indicates that the high pressure switch has been activated, causing the system to shut down. This is a safety feature designed to prevent damage to the compressor. The most common causes of this error are a refrigerant leak, a faulty expansion valve, or a clogged air filter.
Low Voltage/Overcurrent
The U2 error code on your Mitsubishi HVAC system indicates a low voltage or overcurrent issue. This could be due to a faulty component drawing too much power or a wiring problem. The system has entered a protective mode to prevent further damage. It's important to address this issue promptly to avoid potential damage to your system.
Discharge Thermistor Short/Open
The U3 error code on your Mitsubishi HVAC system indicates a problem with the discharge thermistor. This component measures the temperature of the air leaving your system, helping to maintain optimal cooling and heating. If the thermistor is shorted or open (not functioning), your system can't accurately monitor this temperature, leading to inefficient operation and potential system damage. Your system has entered a lockout mode to prevent further issues.
Outdoor Thermistor Short/Open
The U4 error code on your Mitsubishi HVAC system indicates a short or open circuit in the outdoor thermistor. The thermistor is a temperature-sensing component that plays a crucial role in maintaining your system's optimal performance. When it malfunctions, your HVAC system may not accurately sense the outdoor temperature, leading to incorrect operation and potential comfort issues.
Abnormal Condenser Temp
The U5 error code on your Mitsubishi HVAC system indicates that the condenser temperature is higher than normal. This could be due to a few reasons, such as a dirty condenser coil, a faulty temperature sensor, or a problem with the refrigerant system. It's important to address this issue promptly to prevent further damage to your system.