Mitsubishi Electric · A major brand in the UK. 72 codes across 11 product families, each taken from the manufacturer’s manuals. Mitsubishi Electric technical support ↗
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72 codes
| Code | Meaning | Stops? | Homeowner check? |
|---|---|---|---|
| A* | M-NET communication error (A* codes) | Yes | Yes |
| E0 | Main remote controller communication failure - reception error (remote controller receives no signal from FTC ref. address 0 for 3 minutes) | Yes | Yes |
| E1 | Main remote controller control board failure - cannot access non-volatile memory | Yes | Yes |
| E2 | Main remote controller control board failure - internal clock fault | Yes | Yes |
| E3 | Main remote controller communication failure - transmission error (remote controller cannot transmit / data mismatch) | Yes | Yes |
| E4 | Main remote controller communication failure - reception error at FTC (no data from main remote controller for 3 min / no signal for 2 min) | Yes | Yes |
| E5 | Main remote controller communication failure - transmission error at FTC (no empty transmission path for 3 min / data mismatch 30 times) | Yes | Yes |
| E6 | Indoor (FTC)/outdoor communication failure - reception error (FTC receives no/incomplete signal for 6 min after power-on or 3 min in operation) | Varies by model | Yes |
| E7 | Indoor (FTC)/outdoor communication failure - transmission error (FTC sends '0' but receives '1' 30 consecutive times) | Yes | Yes |
| E8 | Indoor/outdoor unit communication error - signal receiving error detected by outdoor unit (nothing received normally for 3 minutes) | Yes | Yes |
| E9 | Outdoor unit receives no signal from indoor unit (FTC) | Yes | Yes |
| EA | Indoor/outdoor unit connector miswiring, excessive number of units (2 units or more): outdoor board cannot confirm number of connected FTC/indoor units within 4 minutes of power-on | Yes | Yes |
| EB | Miswiring of indoor/outdoor unit connecting wire (reverse wiring or disconnection): indoor unit number cannot be set within 4 minutes of power-on | Yes | Yes |
| EC | Start time exceeded: outdoor microcomputer cannot receive communication | Yes | Yes |
| ED | Serial communication error between outdoor controller circuit board and outdoor power circuit board | Yes | Yes |
| EE | Combination error between FTC and outdoor unit | Yes | Yes |
| EF | Non defined check code: displayed when a non-defined check code is received | Yes | Yes |
| F3 | 63L connector open (low pressure switch connector circuit open) | Yes | Yes |
| F5 | 63H connector open (high pressure switch connector circuit open) | Yes | Yes |
| F9 | 2 connectors open (both 63H and 63L connector circuits open) | Yes | Yes |
| FB | FTC2 unit control system error (memory error, etc.) | Yes | Yes |
| FC | Abnormality in outdoor unit control system (detected on outdoor microcomputer) | Yes | Yes |
| FD | Detection of abnormal AC voltage: input voltage to outdoor unit 70 V or less | Yes | Yes |
| J0 | Communication failure between FTC and wireless receiver | Partly | Yes |
| J1 | Communication failure between wireless receiver and wireless remote controller (address 1) | Partly | Yes |
| J2 | Communication failure between wireless receiver and wireless remote controller (address 2) | Partly | Yes |
| J3 | Communication failure between wireless receiver and wireless remote controller (address 3) | Partly | Yes |
| J4 | Communication failure between wireless receiver and wireless remote controller (address 4) | Partly | Yes |
| J5 | Communication failure between wireless receiver and wireless remote controller (address 5) | Partly | Yes |
| J6 | Communication failure between wireless receiver and wireless remote controller (address 6) | Partly | Yes |
| J7 | Communication failure between wireless receiver and wireless remote controller (address 7) | Partly | Yes |
| J8 | Communication failure between wireless receiver and wireless remote controller (address 8) | Partly | Yes |
| J9 | Communication failure between FTC (main) and FTC (sub/slave) - multiple outdoor units control (FTC4: between main controller and FTC4 slave) | Yes | Yes |
| L3 | Circulation water temperature overheat protection (primary flow/return water too hot) | Yes | Yes |
| L4 | DHW tank water temperature overheat protection | Yes | Yes |
| L5 | Thermistor (Return water temp.) (THW2) failure | Partly | Yes |
| L6 | Circulation water freeze protection | Yes | Yes |
| L8 | Heating operation error (flow temperature does not rise as expected / thermistor dislodged) | Yes | Yes |
| L9 | Low primary circuit flow rate detected by flow switch | Yes | Yes |
| LA | Pressure sensor failure | Yes | Yes |
| LB | High pressure protection | Yes | Yes |
| LC | Boiler circulation water temperature overheat protection (hybrid/boiler systems) | Yes | Yes |
| LD | Boiler temperature thermistor (THWB1, THWB2) failure | Partly | Yes |
| LE | Boiler operation error (boiler running but zone flow stays cold) | Partly | Yes |
| LF | Flow sensor failure | Yes | Yes |
| LH | Boiler circulation water freeze protection | Yes | Yes |
| LJ | DHW operation error (type of external plate HEX) | Yes | Yes |
| LL | Setting errors of DIP switches on FTC4 control board (boiler, 2-zone, multiple outdoor units) | Yes | Yes |
| LP | Out of water flow rate range for outdoor heat pump unit | Yes | Yes |
| LU | Water circulation pump failure (pump 1 or pump A PWM feedback 83-92% for 10 s) | Yes | Yes |
| P1 | Flow water (TH1) sensor error | Partly | Yes |
| P2 | Thermistor (Ref. liquid temp.) (TH2) failure (FTC2: Refrigerant liquid pipe (TH2) sensor error) | Yes | Yes |
| P6 | Freezing/Overheating protection operation | Yes | Yes |
| P8 | Pipe temperature abnormality (refrigerant temperatures do not change as expected after compressor start) | Yes | Yes |
| P9 | Thermistor (Tank water temp.) (THW5 / TH5) failure - actual tank temperature sensor error | Partly | Yes |
| PE | Inlet water temperature abnormality (return water THW2 too cold during compressor operation) | Yes | Yes |
| U1 | Excessive high pressure: high pressure switch (HPS, 15 MPa, N.C., connector CN934) operated | Yes | Yes |
| U2 | Overheat discharge temperature: discharge thermistor (THERMO_ASSY DIS, TH1) detects 130C or higher | Yes | Yes |
| U3 | Short circuit or disconnection of discharge temperature thermistor (TH1) | Yes | Yes |
| U4 | Short circuit or disconnection of defrost temperature thermistor (TH2) | Varies by model | Yes |
| U5 | Temperature of heat sink (TH8 over-temperature on inverter heat sink) | Yes | Yes |
| U6 | Power module abnormality: checked by driving power module when overcurrent detected (UF or UP condition) | Yes | Yes |
| U7 | Too low superheat due to low discharge temperature | Yes | Yes |
| U8 | Outdoor fan motor: rotational frequency abnormal / not detected during DC fan motor operation | Yes | Yes |
| U9 | Abnormal voltage error (see service handbook) | Yes | Yes |
| UA | Low ambient loop flow rate (flow switch operated below 5.5 L/min during compressor operation) | Yes | Yes |
| UD | Overheat protection: outdoor liquid pipe TH3 or condensing temperature (63HS) >= 70C during compressor operation | Yes | Yes |
| UE | Abnormal pressure of pressure sensor 63HS (63HS detects 0.1 MPa or less) | Yes | Yes |
| UF | Compressor overcurrent interruption (when compressor locked): overcurrent within 30 seconds of compressor start | Yes | Yes |
| UH | Current sensor error or input current error | Yes | Yes |
| UL | Low pressure (abnormal low pressure detected after compressor starts heating operation) | Yes | Yes |
| UP | Overcurrent abnormality: overcurrent detected by secondary current | Yes | Yes |