Mitsubishi Electric Aircon Error Codes

Likely cause: Indoor room-air sensor disconnected, open or short circuit.

What to do: Needs a technician to check and reconnect or replace the sensor.

Likely cause: Indoor liquid-pipe sensor disconnected, open or short circuit.

What to do: Needs a technician to check the wiring and replace the sensor if faulty.

Likely cause: Drain float/level sensor open or short circuit, or wiring fault.

What to do: Needs a technician to inspect and replace the drain sensor.

Likely cause: Failed or jammed drain pump, or a blocked/overflowing condensate drain.

What to do: Clearing the choked drain and pump resolves it — book a chemical wash with drainage clearing.

Likely cause: Reduced airflow from a dirty filter or coil, or low refrigerant icing the coil.

What to do: A choked/iced coil is fixed by a chemical wash; if it persists, have refrigerant level checked.

Likely cause: Often refrigerant leakage; can also be a closed stop valve, wrong pipe connection, or a dislodged pipe thermistor.

What to do: Have a technician check for a refrigerant leak and confirm the stop valves are open.

Likely cause: TH5 coil pipe sensor disconnected, open or short circuit.

What to do: Needs a technician to refit or replace the thermistor.

Likely cause: Compressor protection triggered — e.g. overload, refrigerant shortage, or an electrical fault.

What to do: Needs a technician for compressor and electrical diagnosis.

Likely cause: Faulty remote signal, wiring, or comms voltage between remote and indoor unit.

What to do: Needs a technician to check the remote and its wiring.

Likely cause: Often the outdoor unit powered before the indoor unit, or faulty interconnecting wiring/PCB.

What to do: A power reset to both units may clear it; otherwise a technician must check wiring and the PCB.

Likely cause: Faulty interconnecting wiring or control board between indoor and outdoor units.

What to do: Try a power reset; if it returns, a technician must check wiring and PCBs.

Likely cause: Compressor overheating, usually from insufficient/leaking refrigerant, a faulty discharge thermistor, or extreme conditions.

What to do: Have a technician check the refrigerant charge for a leak before topping up.

Likely cause: Outdoor discharge thermistor open or short circuit.

What to do: Needs a technician to replace the discharge thermistor.

Likely cause: Compressor drawing excess current, or a faulty inverter/power module on the outdoor PCB.

What to do: Needs a technician for inverter output and electrical testing.

Likely cause: High-side over-pressure, commonly a closed stop (ball) valve, dirty/blocked outdoor coil, or restricted airflow.

What to do: Confirm stop valves are open; a dirty condenser coil is cleared by a chemical wash, otherwise a technician is needed.