Perth's Mitsubishi Heavy Industries fault code lookup
Mitsubishi Heavy Industries fault codes decoded
64 codes covered — what each one means, the likely cause, and whether it's worth trying something yourself before booking. Compiled from Mitsubishi Heavy Industries documentation.
Mitsubishi Heavy Industries wall splits (Avanti, Bronte and earlier SRK series) have no code display on the handset — they signal faults by flashing the RUN and TIMER lamps on the indoor unit, and the tables below map every pattern to its E-code equivalent. Ducted, cassette and multi-split systems show the E-code directly on the wired controller.
How to find your Mitsubishi Heavy Industries fault code
Wall splits — count the RUN and TIMER lamps
- 1 There's no code on the handset — the indoor unit's RUN (green) and TIMER (orange) lamps do the talking. Watch one full cycle before the pause.
- 2 RUN flashes 1–7 times while TIMER stays LIT = an indoor-unit fault. Count the RUN flashes.
- 3 RUN flashes continuously while TIMER flashes 1–5 times = an outdoor sensor fault. Count the TIMER flashes.
- 4 RUN stays LIT while TIMER flashes 1–7 times = an outdoor compressor or power fault. Count the TIMER flashes.
- 5 Two special patterns: RUN on + TIMER flashing continuously = cooling high-pressure protection (E35); RUN ×2 + TIMER ×2 = rotor lock (E60).
Wired controllers & ducted systems
- 1 On RC-EX3A / RC-EX3 controllers the code appears on screen automatically (e.g. “Prot.stp.ON E36”) and the operation lamp turns red.
- 2 Older RC-E5 controllers alternate “INSPECT UNIT” with the E-code.
- 3 Past faults are kept in the Error History under the Menu — handy if the code cleared before you looked.
- 4 If no code shows on a controller, check it hasn't been switched off in the display settings.
Mitsubishi Heavy Industries fault code tables
Wall-mounted splits (Avanti SRK-ZSA / Bronte SRK-ZRA & earlier SRK series) — indoor-unit faults: RUN lamp flashes N times, TIMER lamp stays on
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| RUN ×1 + TIMER on | Indoor heat-exchanger (coil) temperature sensor 1 fault — the unit can no longer read its indoor coil temperature | Broken sensor wire or loose connector plug; occasionally a faulty indoor PCB | Book a service |
| RUN ×2 + TIMER on | Room temperature sensor fault — the unit can't read the room air temperature | Broken room-sensor wire or poor connector contact; occasionally a faulty indoor PCB | Book a service |
| RUN ×3 + TIMER on | Indoor heat-exchanger temperature sensor 2 fault | Broken sensor wire or poor connector connection; occasionally a faulty indoor PCB | Book a service |
| E9 / RUN ×4 + TIMER on | Condensate drain fault — the float switch has detected water backing up in the drain tray (applies to multi-split and concealed indoor units with a drain pump) | Blocked or kinked condensate drain, failed drain pump, or drain run with the wrong fall | Try this first Switch the unit off and check the condensate drain outlet outside for kinks, debris or blockage and clear it; if water keeps backing up or the fault returns, book a service before water damage occurs |
| E47 / RUN ×5 + TIMER on | Active filter / supply voltage fault — the outdoor unit has detected the wrong voltage on its power supply | Incorrect or unstable power supply voltage, defective active filter, or faulty outdoor PCB | Switch off & call |
| E16 / RUN ×6 + TIMER on | Indoor fan motor fault — the indoor fan is turning too slowly (under about 300 rpm) or not at all | Defective fan motor, poor connector connection, or something obstructing the fan; occasionally a faulty indoor PCB | Book a service |
| E57 / RUN ×7 + TIMER on | Refrigeration-cycle protective control has operated — the system has stopped to protect itself. | A service valve on the outdoor unit left closed (check this first — opening it fixes the fault with no regas needed), or insufficient refrigerant. | Switch off & call |
Wall-mounted splits — outdoor sensor faults: RUN lamp keeps flashing continuously, count the TIMER lamp flashes
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| E38 / RUN continuous + TIMER ×1 | Outdoor air temperature sensor fault | Broken outdoor air-sensor wire or poor connector connection; occasionally a faulty outdoor PCB | Book a service |
| E37 / RUN continuous + TIMER ×2 | Outdoor heat-exchanger (coil) temperature sensor fault | Broken sensor wire or poor connector contact; occasionally a faulty outdoor PCB | Book a service |
| E39 / RUN continuous + TIMER ×4 | Compressor discharge-pipe temperature sensor fault | Broken discharge-pipe sensor wire or poor connector connection; occasionally a faulty outdoor PCB | Book a service |
| E53 / RUN continuous + TIMER ×5 | Compressor suction-pipe temperature sensor fault (multi-split outdoor units) | Broken suction sensor wire or poor connector connection | Book a service |
Wall-mounted splits — compressor / power faults: RUN lamp stays on, count the TIMER lamp flashes (plus two special patterns)
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| E42 / RUN on + TIMER ×1 | Current cut — the compressor drew too much current and the unit shut it down to protect itself | Compressor locking, open phase on the compressor output, shorted power transistor, or a closed service valve | Switch off & call |
| E59 / RUN on + TIMER ×2 | Outdoor unit trouble — an emergency stop caused by a fault in the outdoor unit | Defective power transistor, broken compressor wire, compressor blockage, or input current measured abnormally low | Switch off & call |
| E58 / RUN on + TIMER ×3 | Current-safe stop — the compressor could not reach its commanded speed and the overcurrent protection operated | Overload operation (blocked airflow), refrigerant overcharge, or compressor locking | Switch off & call |
| E51 / RUN on + TIMER ×4 | Power transistor fault — the inverter drive that runs the compressor has failed | Broken power transistor, faulty inverter/main PCB, or a faulty fan motor | Switch off & call |
| E36 / RUN on + TIMER ×5 | Compressor overheat — the discharge-pipe temperature has exceeded its safe limit | Refrigerant shortage (gas leak), defective discharge-pipe sensor, or a closed service valve | Switch off & call |
| E5 / RUN on + TIMER ×6 | Signal transmission error — the indoor and outdoor units have stopped talking to each other | Power supply problem, broken or loose interconnecting cable, or a defective indoor/outdoor PCB | Try this first Turn the system off at the isolator or breaker, wait 2 minutes, then restore power — a power glitch often causes this; if the code returns, book a service (it needs a wiring check) |
| E48 / RUN on + TIMER ×7 | Outdoor fan motor fault — the outdoor fan is turning too slowly or not at all | Defective outdoor fan motor, poor connector connection, or the fan physically obstructed by debris | Try this first Switch off at the breaker and clear leaves, grass or debris from around and on top of the outdoor unit, then restore power after 2 minutes; if the fan still won't run or the code returns, book a service |
| E35 / RUN on + TIMER flashing continuously | Cooling high-pressure protection — the outdoor heat exchanger got too hot while cooling and the unit shut down to protect the compressor. | Blocked or dirty outdoor coil, restricted airflow around the outdoor unit, refrigerant overcharge, a broken outdoor coil sensor wire, or a closed service valve. | Try this first Switch off and clear debris, vegetation and anything stacked around the outdoor unit so air can flow freely through the coil, then power-cycle for 2 minutes; if it trips again, book a service |
| E60 / RUN ×2 + TIMER ×2 | Rotor lock — the compressor motor's rotor position can't be detected and the compressor won't start | Defective compressor, open phase on the compressor wiring, or a faulty outdoor PCB | Switch off & call |
| E40 (wall splits) | Gas-side service valve closed — the inverter current spiked because refrigerant can't circulate (shown on a wired controller; compressor stops in heating) | Service valve on the outdoor unit left closed or not fully open; possible refrigerant contamination or faulty outdoor PCB | Switch off & call |
| E1 (no lamp pattern) | Wired remote-controller wiring error — the optional wall controller has lost communication with the indoor unit | Broken controller wire, X/Y wires reversed, electrical noise on the controller lines, or a faulty controller/indoor PCB | Try this first Power-cycle at the breaker for 2 minutes — noise-induced faults often clear; if the controller still shows E1, book a service to check the controller wiring |
Ducted, cassette & multi-split indoor units on wired controllers (E-code shown on RC-EX3A / RC-EX3 / RC-E5 display) — FDU/FDUA/FDUM ducted, FDT/FDTC cassettes, SCM multi outdoor
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| E1 | Communication error between the wired controller and the indoor unit | Broken or reversed controller wires, electrical noise on the controller lines, or a faulty controller/indoor PCB | Try this first Turn the system off at the isolator/breaker, wait 2 minutes and restore power; if E1 returns, book a service |
| E2 | Duplicated indoor unit address (multi-unit installations) | Two indoor units set to the same address, or too many indoor units connected — an installer configuration issue | Book a service |
| E3 | Indoor–outdoor signal transmission error — on residential splits E3 (with E5) means the indoor and outdoor units have stopped communicating. | Power supply problem, broken or loose interconnecting cable, or a faulty indoor/outdoor PCB. (On commercial KX/VRF equipment E3 instead indicates an outdoor signal-line or pairing fault.) | Book a service |
| E5 | Communication error during operation — indoor and outdoor units stopped talking mid-run | Power lost to the outdoor unit, broken signal wire, electrical noise, or a faulty PCB | Try this first Check nothing has tripped the outdoor unit's breaker, then power-cycle the whole system at the breaker for 2 minutes; if E5 returns, book a service |
| E6 | Indoor heat-exchanger (coil) temperature thermistor fault | Defective thermistor (broken wire or short-circuit) or poor connector contact; occasionally the indoor PCB | Book a service |
| E7 | Indoor return-air temperature thermistor fault | Defective return-air thermistor or poor connector contact; occasionally the indoor PCB | Book a service |
| E8 | Heating overload — the indoor coil temperature is abnormally high in heating | Restricted indoor airflow (dirty filters, blocked return or closed outlets), a faulty coil sensor, or faulty indoor PCB | Try this first Switch off, clean the return-air filters and make sure the return grille and supply outlets aren't blocked, then restart; if E8 returns with clean filters, book a service |
| E9 | Drain fault — the float switch has detected condensate backing up in the drain tray | Blocked condensate drain, failed drain pump, broken pump wire, or a stuck float switch | Try this first Check the condensate drain outlet for blockage or kinks and clear it; if water keeps accumulating or E9 returns, book a service promptly to avoid ceiling water damage |
| E10 | Too many indoor units (more than 16) connected to one remote controller | Installer configuration error on a multi-unit installation | Book a service |
| E11 | Address setting error of indoor units (attempt to set master indoor unit address incorrectly when multiple indoor units share one remote controller) | Incorrect address/DIP-switch configuration during installation or after a PCB swap on multi-indoor-unit setups. | Book a service |
| E12 | Address setting error — mixed address setting methods (automatic and manual) on the same system | Installer configuration fault: some units set to auto-address, others manually addressed. | Book a service |
| E14 | Communication error between master and slave indoor units | Broken or loose signal wiring between paired indoor units, wrong master/slave address settings, or indoor PCB fault. Seen on twin/triple ducted configurations where multiple indoor units run off one controller. | Book a service |
| E16 | Indoor fan motor fault (FDT/FDTC/FDU/FDUM series) — fan speed abnormal or motor stopped | Faulty indoor fan motor, poor connection, foreign matter in the fan, or a faulty indoor PCB | Book a service |
| E19 | Indoor unit operation-check / drain-motor check-mode anomaly | Unit left in a check/test mode, or a drain motor wiring fault | Book a service |
| E20 | Indoor fan motor rotation speed anomaly (DC fan motor cannot reach or report correct speed) | Fan blocked by foreign matter, failed DC fan motor, or indoor PCB fault. Documented in FDT/FDU/FDUM/FDF service manuals — one of the most common real-world faults on ducted and cassette indoor units alongside E16. | Book a service |
| E28 | Wired remote controller's built-in temperature sensor fault | Broken wire or defective thermistor inside the wall controller | Book a service |
| E30 | Unmatched (incompatible) connection between indoor and outdoor unit | Indoor and outdoor models are not a valid combination — typically appears after a PCB replacement with wrong settings or a mismatched changeover install. | Book a service |
| E32 | Open L3 phase or reversed phase in the primary power supply to the outdoor unit | Lost phase on a 3-phase supply (tripped breaker, blown phase fuse, supply-side outage) or phases wired in wrong rotation. Very common on Australian 3-phase ducted systems after power interruptions — customers can check the switchboard for a tripped 3-phase breaker before calling; correcting phase order or a lost phase needs an electrician. | Try this first |
| E33 | Anomalous current detected on the inverter primary (power-supply) side of the outdoor unit — a supply-side fault, not a compressor overcurrent trip. | Power supply problem or faulty outdoor inverter PCB. (Compressor current-cut is the separate code E42.) | Switch off & call |
| E34 | Open L3 phase in the power supply (three-phase ducted outdoor units) | A lost phase in the incoming three-phase supply, blown fuse, or wiring fault | Switch off & call |
| E35 | Cooling overload — the outdoor heat-exchanger temperature climbed too high while cooling | Blocked/dirty outdoor coil or restricted airflow around the outdoor unit; defective coil thermistor; closed service valve | Try this first Switch off and clear debris and vegetation from around the outdoor unit so air can flow through the coil freely, then power-cycle for 2 minutes; if E35 returns, book a service |
| E36 | Discharge temperature error — the compressor's discharge pipe got dangerously hot | Refrigerant shortage (leak), closed service valve, or a defective discharge-pipe thermistor | Switch off & call |
| E37 | Outdoor heat-exchanger temperature thermistor fault | Defective thermistor, broken wire, or poor connector connection; occasionally the outdoor PCB | Book a service |
| E38 | Outdoor air temperature thermistor fault | Defective outdoor air thermistor, broken wire, or poor connector connection | Book a service |
| E39 | Discharge-pipe temperature thermistor fault | Defective discharge thermistor, broken wire, or poor connector connection | Book a service |
| E40 | High-pressure fault — the high-pressure switch (63H1) operated and shut the system down | Poor airflow across a coil (blocked outdoor unit in cooling, blocked filters/returns in heating), closed service valve, or a faulty high-pressure switch/PCB | Switch off & call |
| E41 | Power transistor overheat — the inverter's drive stage overheated (detected twice within an hour) | Faulty power transistor or its temperature sensor, poor heat-sink cooling, or a faulty inverter PCB | Switch off & call |
| E42 | Current cut — compressor overcurrent protection operated | Compressor locking, open phase on compressor output, shorted power transistor, or closed service valve | Switch off & call |
| E44 | Liquid flood-back — liquid refrigerant is returning to the compressor during cooling (detected 3 times in 90 minutes) | Refrigerant overcharge, expansion-valve problem, or abnormal operating conditions — risks compressor damage | Switch off & call |
| E45 | Communication error between the inverter PCB and the outdoor control PCB | Faulty outdoor sub/main PCB or poor connection of the wires between the outdoor boards | Book a service |
| E47 | Inverter over-voltage / active filter fault | Wrong or unstable supply voltage, defective active filter, or faulty outdoor main PCB | Switch off & call |
| E48 | Outdoor (DC) fan motor fault — the outdoor fan speed stayed below its minimum | Defective outdoor fan motor, poor connector connection, debris obstructing the fan, or a faulty outdoor PCB | Try this first Switch off at the breaker, clear leaves and debris from around and on top of the outdoor unit, then restore power after 2 minutes; if the code returns, book a service |
| E49 | Low-pressure fault — refrigerant pressure fell below the safe limit | Refrigerant leak, closed service valve, or a broken low-pressure sensor wire | Switch off & call |
| E51 | Power transistor / inverter fault detected at compressor start | Broken power transistor, faulty inverter or main PCB, or a faulty fan motor | Switch off & call |
| E53 | Suction-pipe temperature thermistor fault | Defective suction thermistor, broken wire, or poor connector connection | Book a service |
| E54 | Low-pressure (or high-pressure) sensor fault | Faulty pressure sensor or outdoor control PCB | Book a service |
| E55 | Compressor under-dome temperature thermistor fault | Defective under-dome thermistor, broken wire, or poor connector connection | Book a service |
| E56 | Power transistor temperature thermistor (Tho-P1/Tho-P2) anomaly on the outdoor inverter | Broken wire, poor connector contact, or failed thermistor on the outdoor inverter power module; documented in the FD-series outdoor fault tables alongside E36-E39 sensor codes. | Book a service |
| E57 | Insufficient refrigerant — the refrigeration-cycle protection has operated | Refrigerant leak / short charge, or a service valve left closed after installation | Switch off & call |
| E58 | Current-safe stop / compressor loss of synchronisation — the compressor can't hold its commanded speed | Overload operation, refrigerant overcharge, or compressor locking | Switch off & call |
| E59 | Compressor start-up failure | Faulty compressor, faulty inverter circuit/PCB, or wiring fault to the compressor | Switch off & call |
| E60 | Compressor rotor position detection failure (rotor lock) | Defective compressor, open phase on the compressor wiring, or a faulty outdoor PCB | Switch off & call |
No matching code found.
Meanings vary by series and some codes are model-specific — call 0434 951 341 with the code and your model number and we'll decode it.
Reference compiled from Mitsubishi Heavy Industries service and operation documentation. Codes and meanings are provided as general guidance for the Australian residential range and can differ between model series; no affiliation with Mitsubishi Heavy Industries is implied.
Tell us the code when you book — diagnosis starts before we arrive
Air conditioning service and repairs across Perth from $220 inc GST — all brands, splits and ducted. Quoting the fault code gives us a head start on where to look; we then test and confirm the actual fault on site before any part is ordered, so you never pay for a part you didn't need.
Frequently Asked Questions
How do I read the flashing lights on my MHI air conditioner?
Watch one full flash cycle on the indoor unit. If the RUN lamp flashes and TIMER stays lit, count the RUN flashes — that's an indoor fault. If RUN flashes continuously and TIMER flashes in bursts, count the TIMER flashes — that's an outdoor sensor fault. If RUN stays lit and TIMER flashes, count the TIMER flashes — that's a compressor or power fault. The step-by-step is above the tables on this page.
Is Mitsubishi Heavy Industries the same as Mitsubishi Electric?
No — they're separate companies with completely different air conditioners and completely different fault codes. MHI uses E-numbers and RUN/TIMER lamp patterns; Mitsubishi Electric uses blink counts and P/U/F check codes. Make sure you're reading the right table: check the badge on your indoor unit.
My MHI shows E57 — do I need a regas?
Not necessarily, and this one's worth knowing: E57 has two official causes, and a closed service valve is the first. If the system was recently installed or serviced, an unopened valve produces the same code as low refrigerant — one costs nothing to fix. Get it diagnosed before anyone quotes you gas.
Can I reset an MHI fault code?
Switch off at the isolator or breaker, wait two minutes, then restore power. One-off trips from power glitches clear and stay cleared. If the same lamp pattern returns, the fault is genuine and needs diagnosing rather than repeated resetting.
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