Free reference

Aircon fault code lookup.

Search or filter by brand to decode what a flashing error on your split, ducted or multi-head aircon actually means. Each entry lists the likely cause and the first thing to check before booking a service call. Covers every major brand we install plus the ones we don’t.

Brand	System	Code	Likely meaning	First check
Mitsubishi Electric	Air conditioner	P1	Indoor room-thermistor fault	Indoor unit thermistor loose or failed — needs a service call.
Mitsubishi Electric	Air conditioner	P2	Indoor pipe-thermistor fault	Pipe sensor open-circuit — usually a swap-out fix.
Mitsubishi Electric	Air conditioner	P4	Drain sensor fault	Check the condensate drain pan isn't clogged; sensor may need replacing.
Mitsubishi Electric	Air conditioner	P5	Drain pump fault	Condensate pump seized or blocked — clear the drain line and re-test.
Mitsubishi Electric	Air conditioner	P6	Coil frost / overheat protection	Filter blocked or airflow restricted. Clean filters + check outdoor coil.
Mitsubishi Electric	Air conditioner	P8	Pipe temperature abnormal	Low refrigerant charge or restriction. Needs an ARC-licensed tech.
Mitsubishi Electric	Air conditioner	E0	Remote-control transmission error	Wired controller comms drop — check controller wire terminations.
Mitsubishi Electric	Air conditioner	E6	Indoor / outdoor comms failure	Check the S1-S2-S3 comms wire between indoor & outdoor units.
Mitsubishi Electric	Air conditioner	E9	Indoor / outdoor comms error (variant)	Same as E6 — comms cable, check for damage or loose terminals.
Mitsubishi Electric	Air conditioner	U2	Compressor overheat / oil shortage	STOP using the unit. Compressor at risk — book a warranty service call.
Mitsubishi Electric	Air conditioner	U4	Outdoor thermistor open-circuit	Outdoor coil or discharge sensor faulty. Tech required.
Daikin	Air conditioner	A1	Indoor PCB defect	Indoor board fault — power-cycle the unit first, then service if it returns.
Daikin	Air conditioner	A5	High-pressure control / freeze-up protection	Filter dirty or outdoor coil blocked. Clean both, re-test.
Daikin	Air conditioner	A6	Indoor fan motor fault	Fan motor stalled or capacitor failed. Service call.
Daikin	Air conditioner	C4	Indoor heat-exchanger thermistor fault	Sensor open-circuit — swap-out fix.
Daikin	Air conditioner	C9	Indoor air suction thermistor fault	Room-temp sensor failed. Service call.
Daikin	Air conditioner	E1	Outdoor PCB defect	Outdoor board fault. Power-cycle first, then book service.
Daikin	Air conditioner	E5	OL activated (compressor overload)	STOP unit. Compressor overload — likely refrigerant charge or fan issue.
Daikin	Air conditioner	E6	Compressor lock / start failure	STOP unit. Compressor won't spin up. Warranty / service.
Daikin	Air conditioner	E7	Outdoor fan motor lock	Check for debris jamming the outdoor fan. If clear, motor swap.
Daikin	Air conditioner	F3	Discharge-pipe temperature too high	Low refrigerant charge or blocked outdoor coil. ARC tech needed.
Daikin	Air conditioner	L5	Inverter compressor abnormal	STOP unit. Inverter fault — warranty repair.
Daikin	Air conditioner	U0	Refrigerant shortage	Refrigerant low — check for leak, book an ARC-licensed tech.
Daikin	Air conditioner	U4	Indoor / outdoor comms error	Check the F1-F2 comms wire — loose terminal or damaged cable.
Fujitsu	Air conditioner	E:EE	Room-temp thermistor fault	Thermistor open — sensor swap.
Fujitsu	Air conditioner	E:11	Comms error indoor ↔ outdoor	Comms wire fault. Check terminals both ends.
Fujitsu	Air conditioner	E:12	Outdoor comms not responding	Outdoor board or power supply — book service.
Fujitsu	Air conditioner	E:14	Signal transmission error (wired remote)	Wired controller — check the H1-H2 line terminations.
Fujitsu	Air conditioner	OP:00	Outdoor high-pressure protection	Airflow blocked at outdoor unit. Clear obstructions and re-test.
Fujitsu	Air conditioner	OP:04	Compressor discharge-temp protection	STOP unit. Likely low charge or blocked coil.
Panasonic	Air conditioner	H11	Indoor / outdoor comms failure	Comms cable fault. Check terminals.
Panasonic	Air conditioner	H15	Compressor sensor error	Sensor failed — service call.
Panasonic	Air conditioner	H27	Outdoor air sensor error	Sensor open — swap-out fix.
Panasonic	Air conditioner	F91	Refrigerant abnormal (leak)	STOP unit. Refrigerant leak — ARC tech needed.
Panasonic	Air conditioner	F99	Outdoor DC over-current	STOP unit. Inverter / compressor fault. Warranty service.
LG	Air conditioner	CH01	Indoor room-thermistor error	Sensor open — swap fix.
LG	Air conditioner	CH02	Indoor pipe sensor error	Sensor open — swap fix.
LG	Air conditioner	CH05	Indoor / outdoor comms error	Comms cable — check terminals both ends.
LG	Air conditioner	CH21	IPM fault (inverter power module)	STOP unit. Inverter power stage — book warranty service.
Kaden	Air conditioner	E1	Indoor & outdoor comms error	Check comms cable connection between heads.
Kaden	Air conditioner	E2	Room temp sensor fault	Sensor open — sensor swap by installer.
Kaden	Air conditioner	E5	Overcurrent protection	Airflow blocked or refrigerant charge low. Service call.
Kaden	Air conditioner	F1	Outdoor unit sensor fault	Outdoor sensor swap — book service.
Kaden	Air conditioner	F3	Compressor discharge temp too high	STOP unit. Likely low charge. ARC tech required.
Brivis	Gas heater	22	Overheat safety limit tripped	Blocked filter or blocked return-air path. Clean filter, reset unit.
Brivis	Gas heater	37	Ignition failure — no gas or dirty igniter	Check gas supply on. If good, needs a gas fitter to inspect the igniter.
Brivis	Gas heater	43	Fan proving switch open	Fan not spinning up. Book gas heater service.
Brivis	Gas heater	50	Communications lost (network wall control)	Check the network wire between the wall control and the heater.
Reclaim	Hot water	E1	Ambient temp sensor fault	Outdoor sensor open-circuit. Book a Reclaim-accredited service tech.
Reclaim	Hot water	E2	Evaporator temp sensor fault	Evaporator sensor fault — swap-out fix by a tech.
Reclaim	Hot water	E3	Discharge / suction sensor fault	Sensor swap by an ARC-licensed tech.
Reclaim	Hot water	E4	Tank temp sensor fault	Tank thermistor open — sensor swap. Water still heats via boost.
Reclaim	Hot water	E5	High-pressure fault (CO2)	STOP unit. Refrigerant charge / heat-exchanger issue. Warranty service.
Reclaim	Hot water	E6	Low-pressure fault (CO2)	STOP unit. Likely refrigerant leak — Reclaim tech required.
Reclaim	Hot water	E7	Compressor overload	STOP unit. Compressor at risk — book warranty service.
Reclaim	Hot water	F1	Comms error tank ↔ heat pump	Check the comms wire between the outdoor heat pump and the tank controller.
iStore	Hot water	E1	Ambient temp sensor fault	Sensor open-circuit. Book service — water will still heat on boost element.
iStore	Hot water	E2	Evaporator sensor fault	Sensor swap by installer.
iStore	Hot water	E3	Condenser sensor fault	Sensor open — service call.
iStore	Hot water	E4	Tank sensor fault	Tank thermistor fault — sensor swap.
iStore	Hot water	E5	Compressor high pressure	STOP unit. Likely blocked evaporator airflow. Clean coil.
iStore	Hot water	E7	Anti-freeze protection triggered	Very cold ambient — normal in winter. If persistent, book service.
iStore	Hot water	E8	Compressor drive fault	STOP unit. Inverter drive fault — warranty repair.
Thermann	Hot water	E1	Water temp sensor fault (integrated HP)	Sensor open — Thermann service call.
Thermann	Hot water	E2	Ambient sensor fault	Sensor open — swap by installer.
Thermann	Hot water	E5	Compressor overload	STOP unit. Book warranty service.
Thermann	Hot water	F1	Comms error (integrated HP)	Check internal comms wire between board and controller.
Thermann	Hot water	12	G-series continuous flow — ignition failure	Check gas supply on. If OK, needs a licensed gas fitter.
Thermann	Hot water	11	G-series — no ignition detected	Gas valve or igniter fault. Book a gas fitter.

Showing 69 of 69 codes

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