DIY HVAC Tools

Mitsubishi Electric mini split error codes

Mitsubishi Electric M-Series and Mr. Slim systems use Mitsubishi's own P, E, F and U code set, shown on a wired controller or read from the remote's check mode.

Covers: M-Series (MSZ), Mr. Slim (PKA/PCA), Hyper-Heating H2i, MXZ multi-zone.

Type it exactly as the unit shows it. Not sure which brand? It is printed on the front of the indoor unit.

Most looked-up Mitsubishi Electric codes

E6Communication error between indoor and outdoor unitsP8Pipe temperature abnormal (refrigerant circuit)U6Power module (IPM) fault or over-currentP6Freeze protection (cooling) or overheat protection (heating)U1High pressure abnormal (high-pressure switch operated)E9Communication error between indoor and outdoor unitsP4Drain sensor or float switch faultU9Voltage abnormal (over-voltage, under-voltage, open phase or PFC)UFCompressor over-current (locked compressor)

All Mitsubishi Electric codes

35 codes. Type to filter the list.

CodeMeaningTypeFix
P1Indoor intake (room) air temperature sensor fault (open or short circuit)FaultDIY checks
P2Indoor pipe (liquid) temperature sensor fault (open or short circuit)FaultDIY checks
P4Drain sensor or float switch faultFaultDIY
P5Drain pump fault (overflow protection)FaultDIY checks
P6Freeze protection (cooling) or overheat protection (heating)ProtectionDIY
P8Pipe temperature abnormal (refrigerant circuit)FaultTechnician
P9Indoor pipe (condenser/evaporator) temperature sensor fault (open or short circuit)FaultDIY checks
E0Remote controller signal receiving errorFaultDIY checks
E1Remote controller control board faultFaultDIY checks
E2Remote controller control board faultFaultDIY checks
E3Remote controller signal transmitting errorFaultDIY checks
E4Indoor unit signal receiving error (from remote controller)FaultDIY checks
E5Indoor unit signal transmitting error (to remote controller)FaultDIY checks
E6Communication error between indoor and outdoor unitsFaultDIY checks
E7Communication error between indoor and outdoor unitsFaultDIY checks
E8Communication error between indoor and outdoor unitsFaultDIY checks
E9Communication error between indoor and outdoor unitsFaultDIY checks
EAMiswiring between indoor and outdoor units, or too many indoor unitsFaultDIY checks
EbMiswiring of indoor/outdoor connecting wiresFaultDIY checks
ECStart-up time over (outdoor unit)FaultTechnician
EdSerial communication error (outdoor unit boards)FaultTechnician
FbIndoor unit control board faultFaultTechnician
U1High pressure abnormal (high-pressure switch operated)ProtectionDIY checks
U2Discharge temperature abnormal (too high)ProtectionDIY checks
U3Compressor discharge temperature sensor (TH4) fault (open or short circuit)FaultDIY checks
U4Outdoor unit temperature sensor open or short (TH3, TH6, TH7 or TH8)FaultDIY checks
U5Inverter heat sink temperature abnormalProtectionDIY checks
U6Power module (IPM) fault or over-currentProtectionTechnician
U7Superheat abnormal (discharge temperature too low)ProtectionTechnician
U8Outdoor fan motor faultFaultDIY checks
U9Voltage abnormal (over-voltage, under-voltage, open phase or PFC)ProtectionDIY checks
UFCompressor over-current (locked compressor)ProtectionTechnician
UHCurrent sensor faultFaultTechnician
ULLow pressure abnormalProtectionDIY checks
UPCompressor over-current interruptionProtectionTechnician

How Mitsubishi Electric shows error codes

Wall units without a wired controller signal a fault by blinking the operation indicator lamp; the code itself shows on a wired controller (MHK/PAR series) or on the wireless remote after entering its check mode (see your manual). On the outdoor unit, the control board LEDs blink the same code. P codes are indoor-unit faults, E codes are communication faults, F codes are outdoor-unit faults and U codes are outdoor-unit and compressor faults.

Brands built on the same platform

These brands share a code table with Mitsubishi Electric because the same factory builds them, so their pages describe the same faults: American Standard, Trane.

Sources

  • Mitsubishi Electric M-Series and Mr. Slim service manuals (self-diagnosis tables)

Updated September 2026. Manufacturer site: www.mitsubishicomfort.com