Mitsubishi Heat Pumps: manuals, user guides and error codes
Looking for a Mitsubishi heat pump manual, user guide, or error code explanation? ServiceMy has created a dedicated resource hub to help homeowners quickly find the information they need for their system.
Our guide library includes downloadable manuals, setup instructions, troubleshooting advice and clear explanations of common error codes. If your Mitsubishi heat pump is showing a fault code, not heating properly, or you simply want to understand how to operate it more efficiently, our guides are designed to help you identify the issue and keep your system running smoothly. These resources are regularly updated and written by experienced heat pump engineers to help you get the most from your heating system, improve efficiency and avoid unnecessary breakdowns.
These apply for the following air source heat pump models:
- PUZ-HWM140VHA
- PUZ-HWM140YHA
- PUZ-WM112VAA
- PUZ-WM112YAA
- PUZ-WM50VHA
- PUZ-WM60VAA
- PUZ-WM85VAA
- PUZ-WM85YAA
- QUHZ-W40VA
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Heat pump malfunctions: Mitsubishi Error Codes
If you cannot find the error code explanation or need help resolving any issues, ServiceMy can help diagnose and arrange a professional heat pump service to restore your system to optimum performance.
| Error Code | Title | Explanation |
| E0 | System Configuration Fault | Incorrect system setup or mismatch between indoor and outdoor units. |
| E1 | Indoor PCB Fault | Internal control board failure; may require reset or replacement. |
| E2 | Remote Controller Communication Fault | Communication issue between controller and indoor unit. |
| E3 | Indoor-Outdoor Communication Fault | Loss of communication between indoor and outdoor units. |
| E4 | Room Temperature Sensor Fault | Indoor air temperature sensor failure. |
| E5 | Pipe Temperature Sensor Fault | Fault with refrigerant pipe temperature sensor. |
| E6 | Indoor Heat Exchanger Sensor Fault | Heat exchanger sensor failure affecting system operation. |
| E7 | Outdoor Unit Fault | General fault reported from outdoor unit. |
| E8 | Indoor Fan Motor Fault | Indoor fan not operating correctly. |
| E9 | Water Temperature Sensor Fault | Fault with water circuit temperature sensor. |
| EA | 4-Way Valve Fault | Reversing valve not switching correctly between heating/defrost. |
| EC | Water Flow Fault | Insufficient water circulation; possible pump issue, airlock, or blockage. |
| ED | Freeze Protection Activated | System protecting against freezing due to low water temperature. |
| EE | EEPROM Fault | Internal memory or configuration error on control board. |
| EF | Flow Temperature Fault | Abnormal flow temperature detected; possible circulation issue. |
| P1 | High Pressure Fault | Refrigerant pressure too high; often due to poor heat transfer or flow issues. |
| P2 | Low Pressure Fault | Refrigerant pressure too low; typically due to leaks or low charge. |
| P4 | Compressor Discharge Temperature Fault | Compressor overheating; may indicate system imbalance or high load. |
| P5 | Drain Pump Fault | Condensate pump failure or blockage. |
| P6 | Compressor Overcurrent | Excess current detected; possible compressor or electrical fault. |
| P8 | Fan Motor Fault (Outdoor) | Outdoor fan failure affecting heat exchange. |
| P9 | Refrigerant Circuit Fault | General refrigerant system issue requiring diagnostics. |
| PA | Capacity / Load Fault | System unable to meet required load; may indicate undersizing or fault condition. |
| U0 | Refrigerant Shortage | Low refrigerant detected; likely leak within system. |
| U1 | Reverse Phase / Power Fault | Incorrect electrical phase or unstable power supply. |
| U2 | Power Supply Fault | Voltage outside acceptable range. |
| U3 | Test Mode / Commissioning Fault | System left in test mode or commissioning incomplete. |
| U4 | Communication Fault (Indoor-Outdoor) | Communication failure between indoor and outdoor units. |
| U5 | Controller Communication Fault | Communication issue with wired controller. |
| U6 | Addressing Fault | Incorrect addressing between system components. |
| U7 | Transmission Fault | Signal transmission error within system. |
| U8 | Duplicate Address Fault | Duplicate addressing detected on system network. |
| U9 | System Communication Fault | General communication error across system. |
| UF | Refrigerant System Fault | General refrigerant fault requiring further investigation. |
| UH | System Addressing / Configuration Fault | Incorrect system configuration or addressing mismatch. |
| L3 | Electrical Box Overheat | Internal electrical components overheating. |
| L4 | Inverter Heat Sink Overheat | Inverter temperature too high; may indicate cooling issue. |
| L5 | Inverter Overcurrent | Compressor inverter overloaded. |
| L8 | Compressor Overload Protection | Compressor operating outside safe limits. |
| L9 | Compressor Lock Fault | Compressor seized or unable to start. |
Schedule Your Heat Pump Service Today
Don’t wait until efficiency drops, or your pump encounters issues. Investing in routine maintenance for your air source heat pump is the best way to keep your household energy-efficient, cosy, and cost-effective year-round.
Get in touch with our professional servicing team today to schedule your appointment. With extensive experience in heat pump servicing and home energy solutions, we’re here to help you stay warm, save money, and protect your investment.
Maintain your heat pump, and it will reward you with years of efficient and reliable performance.
