Mini split and heat pump error codes are short letter-and-number messages — such as E6, P4, or U4 — that a ductless system shows when its control board detects a fault. The code points to the affected area: communication between the indoor and outdoor units, a temperature sensor, the condensate drain, the refrigerant circuit, or the compressor. That lets you tell quickly whether the cause is a simple homeowner fix (a dirty filter, a clogged drain line, a tripped breaker) or a job that needs a licensed technician. The catch: every brand uses its own code set, and meanings can vary by model — so the fastest path is to pick your brand below, find your exact code in its quick-lookup table, and confirm it against your unit’s manual.
How to read any mini-split error code
- Identify your brand and model (look on the indoor or outdoor unit’s label).
- Read the code from the indoor display, the wired controller, or the blinking LED pattern.
- Look it up in your brand’s table below, then do the safe first step.
- If the code returns after one power cycle, stop and call a pro.
Most brands group codes by their first character — for example, communication faults, sensor faults, and compressor/refrigerant protection each tend to share a prefix. The brand guides below break down exactly what each code means for that manufacturer.
Look up your exact code
Don’t want to read every brand? Use the searchable database below: type your code or the symptom, narrow it by brand, and see what it means plus the safe first step. It covers the codes from every brand guide on this site in one place.
Error code lookup — search every brand
Type your code (for example E6, P8, CH05)
or a symptom, and filter 134 verified codes across 8
brands. Each row links to the full brand guide.
Showing all 134 codes
| Brand | Code | What it means | First step | Who fixes it |
|---|---|---|---|---|
| Mitsubishi | E0 / E3 | Remote controller transmission error (signal not sent/received) | Re-seat remote & receiver, then power-cycle | Try yourself |
| Mitsubishi | E1 / E2 | Remote controller board fault | Power-cycle once; if it returns, call a pro | Try yourself |
| Mitsubishi | E4 / E5 | Remote controller signal-receiving error | Check receiver line-of-sight & wiring; power-cycle | Try yourself |
| Mitsubishi | E6 / E7 | Indoor ↔ outdoor communication error (often wiring) | Power-cycle; inspect interconnecting wiring | Try yourself |
| Mitsubishi | E8 / E9 | Indoor/outdoor communication or transmission error | Wiring check; if it persists, call a technician | Try yourself |
| Mitsubishi | EA / Eb / EE | Unit-count / connection / address error | Technician — wiring & addressing | Call a pro |
| Mitsubishi | P1 | Intake (room) air thermistor fault | Technician — sensor | Call a pro |
| Mitsubishi | P2 / P9 | Pipe (liquid/condenser) thermistor fault | Technician — sensor | Call a pro |
| Mitsubishi | P4 | Drain sensor / float switch connector fault | Check drain & float connector; clear any clog | Try yourself |
| Mitsubishi | P5 | Drain pump fault / drain overflow protection | Clear the clogged condensate drain line | Try yourself |
| Mitsubishi | P6 | Coil freeze-up / overheat protection | Clean filter, restore airflow | Try yourself |
| Mitsubishi | P8 | Pipe (refrigerant line) temperature abnormal | Check airflow/filter; if it persists, tech (refrigerant) | Call a pro |
| Mitsubishi | U2 | High discharge temp / overheat / refrigerant shortage | Power off — technician (refrigerant) | Call a pro |
| Mitsubishi | U3 / U4 | Discharge thermistor open/short, or outdoor sensor fault | Technician — sensor | Call a pro |
| Mitsubishi | U5 | Heatsink / power-module overheat | Clear outdoor-unit airflow; if it persists, tech | Try yourself |
| Mitsubishi | U6 / UF | Compressor over-current / power-module fault | Power off — technician (compressor) | Call a pro |
| Mitsubishi | Fb | Indoor unit control board fault | Technician | Call a pro |
| Daikin | U0 | Low refrigerant / refrigerant shortage | Likely a leak — certified technician (EPA 608) | Call a pro |
| Daikin | U2 | Power-supply voltage abnormal (over/under-voltage) | Check breaker & supply voltage | Try yourself |
| Daikin | U4 / UF | Communication fault between indoor & outdoor (often wiring) | Power-cycle; inspect interconnecting wiring | Try yourself |
| Daikin | A1 | Indoor unit PCB (control board) fault | Power-cycle once; if it returns, call a pro | Try yourself |
| Daikin | A5 | High-pressure control / freeze-up protection | Check airflow — clean a dirty filter/coil | Try yourself |
| Daikin | A6 | Indoor fan motor fault or obstruction | Clear obstructions; if it returns, call a pro | Try yourself |
| Daikin | C4 / C9 | Heat-exchanger / suction-air thermistor (sensor) fault | Technician — sensor replacement | Call a pro |
| Daikin | E1 | Outdoor unit PCB (control board) fault | Technician | Call a pro |
| Daikin | E5 | Compressor motor overload / lock (OL) | Power off — technician (compressor) | Call a pro |
| Daikin | E6 | Compressor start fault / locked rotor | Technician | Call a pro |
| Daikin | E7 | Outdoor fan motor fault | Clear debris around the outdoor unit | Try yourself |
| Daikin | F3 | Discharge-pipe temperature too high | Power off — technician (airflow/refrigerant) | Call a pro |
| Daikin | H6 | Compressor position-sensor detection fault | Technician | Call a pro |
| Daikin | L5 | Inverter compressor over-current | Technician | Call a pro |
| Daikin | P4 | Discharge-pipe thermistor (sensor) fault | Technician | Call a pro |
| Fujitsu | 11 | Serial communication error — indoor & outdoor not communicating | Confirm both units have power; power off 3–5 min | Try yourself |
| Fujitsu | 12 | Wired remote controller communication error | Check the remote cable for looseness/damage | Try yourself |
| Fujitsu | 15 | Automatic air-flow adjustment error (fan/louver flow) | Clear obstructions; confirm the indoor fan spins freely | Try yourself |
| Fujitsu | 23 | Combination error — mismatched indoor/outdoor pairing | Technician — verify equipment compatibility | Call a pro |
| Fujitsu | 32 | Indoor PCB model info (EEPROM) error | Reset power; confirm ground. Board fault → pro | Try yourself |
| Fujitsu | 42 | Indoor heat-exchanger (pipe) thermistor error | Technician — sensor/board diagnosis | Call a pro |
| Fujitsu | 51 | Indoor fan motor error — speed below target | Power off; check the indoor fan rotates freely | Try yourself |
| Fujitsu | 53 | Drain pump error — float switch triggered (water build-up) | Check/clear the drain line so condensate drains | Try yourself |
| Fujitsu | 62 | Outdoor main PCB error — EEPROM access failed | Reset power; check for low voltage/poor ground | Try yourself |
| Fujitsu | 63 | Inverter error reported by the inverter PCB | Technician — high-voltage inverter, not DIY | Call a pro |
| Fujitsu | 64 | Active filter / PFC circuit error (inverter DC voltage) | Technician — high-voltage power circuit | Call a pro |
| Fujitsu | 65 | IPM error — abnormal current / blocked heat dissipation | Clear airflow around the outdoor unit; diagnosis → pro | Call a pro |
| Fujitsu | 71 | Discharge thermistor error — sensor open/short | Technician — sensor/board diagnosis | Call a pro |
| Fujitsu | 72 | Compressor thermistor error — sensor open/short | Technician — sensor/compressor circuit | Call a pro |
| Fujitsu | 86 | High-pressure switch / pressure sensor error | Power off 3–5 min; clear outdoor coil/airflow | Call a pro |
| Fujitsu | 94 | Over-current error — compressor protective trip | Technician — compressor electrical fault, not DIY | Call a pro |
| Fujitsu | 95 | Compressor rotor position detection error (permanent stop) | Technician — compressor/inverter fault | Call a pro |
| Fujitsu | 97 | Outdoor fan motor error — speed too low / not turning | Power off; clear debris so the outdoor fan spins | Try yourself |
| MRCOOL | DF | Defrost mode — NOT an error (melting frost off the outdoor coil) | Normal — wait 3–10 min; heating resumes on its own | Not a fault |
| MRCOOL | EH 00 | Indoor EEPROM parameter error (control-board memory) | Power off ~2 min and restart once | Try yourself |
| MRCOOL | EL 01 (E1) | Indoor / outdoor communication error | Check signal/power wiring is tight & correct; both units powered | Try yourself |
| MRCOOL | EH 02 | Zero-crossing signal detection error (AC fan units) | Verify stable power & connections, restart | Try yourself |
| MRCOOL | EH 03 (E3) | Indoor fan speed out of normal range | Power off; confirm blower spins freely; clean filter | Try yourself |
| MRCOOL | EC 07 (F5) | Outdoor fan speed out of normal range | Power off; check outdoor fan for debris/ice | Try yourself |
| MRCOOL | EC 51 (E5) | Outdoor unit EEPROM parameter error | Power off ~2 min and restart | Try yourself |
| MRCOOL | EC 52 | Condenser coil sensor (T3) open/short | Technician — sensor/board diagnosis | Call a pro |
| MRCOOL | EC 53 | Outdoor ambient sensor (T4) open/short | Technician — sensor/board diagnosis | Call a pro |
| MRCOOL | EC 54 | Compressor discharge sensor (TP) open/short | Technician — sensor/board diagnosis | Call a pro |
| MRCOOL | EH 60 | Indoor room sensor (T1) open/short | Technician — sensor/board diagnosis | Call a pro |
| MRCOOL | EH 61 (E5) | Evaporator coil sensor (T2) open/short | Technician — sensor/board diagnosis | Call a pro |
| MRCOOL | EL 0C (EC) | Refrigerant leak detected (low coil temp rise after start) | Technician — refrigerant work requires EPA 608 | Call a pro |
| MRCOOL | PC 00 (P0) | IPM module / IGBT over-current protection | Technician — high-voltage inverter & compressor | Call a pro |
| MRCOOL | PC 01 (P1) | Over-voltage or under-voltage protection | Confirm a correct dedicated circuit & stable voltage | Try yourself |
| MRCOOL | PC 02 (P2) | IPM high-temperature or high-pressure protection | Power off; clear outdoor coil/fan blockage | Try yourself |
| MRCOOL | PC 03 | Low-pressure protection (low refrigerant pressure) | Technician — refrigerant/pressure problem, EPA 608 | Call a pro |
| MRCOOL | PC 04 (P4) | Inverter compressor drive error | Technician — compressor drive/inverter fault | Call a pro |
| MRCOOL | PC 08 | Current overload protection (abnormal current rise) | Power off; check outdoor blockage. Compressor/board → pro | Call a pro |
| Senville | dF / CL / FP | Status messages, NOT faults: defrost / filter reminder / low-temp safeguard | Normal — no repair; clean the filter when CL shows | Not a fault |
| Senville | EH 00 / EH 0A | Indoor EEPROM or parameter error (control-board memory) | Power off ~3 min and restart; returns → pro | Try yourself |
| Senville | EL 01 | Communication failure between indoor & outdoor units | Check signal wires are correct, tight, not crossed; cycle power | Try yourself |
| Senville | EH 02 | Zero-crossing signal detection error (abnormal voltage/frequency) | Confirm a dedicated breaker & stable voltage | Try yourself |
| Senville | EH 03 | Indoor fan speed out of control | Confirm blower not blocked & filter clean | Try yourself |
| Senville | EH 60 | Indoor room temperature sensor (T1) fault | Power-cycle; returns → technician (sensor/board) | Call a pro |
| Senville | EH 61 | Indoor pipe/coil temperature sensor (T2) fault | Power-cycle; persists → technician (sensor) | Call a pro |
| Senville | EH C1 / C2 / C3 | Refrigerant leak detected (or leak sensor out of range) | Technician — refrigerant work requires EPA 608 | Call a pro |
| Senville | FH CC | Refrigerant leak-detection sensor malfunction | Power-cycle; persists → technician | Call a pro |
| Senville | EC 51 | Outdoor EEPROM parameter error (outdoor board memory) | Power off a few minutes; returns → pro | Try yourself |
| Senville | EC 52 / 53 / 54 / 56 | Outdoor sensor faults: coil (T3), ambient (T4), discharge, coil-outlet | Technician — outdoor sensor diagnosis/replacement | Call a pro |
| Senville | EC 07 | Outdoor fan speed out of control (motor or board) | Clear debris around the outdoor unit; persists → pro | Try yourself |
| Senville | EL 0C | System is low on / lacks refrigerant | Technician — diagnosing & recharging requires EPA 608 | Call a pro |
| Senville | PC 00 | IPM module protection (inverter power module) | Power off several minutes, restart once; repeats → tech | Call a pro |
| Senville | PC 01 | Over-/under-voltage (DC bus) protection | Check supply voltage & breaker sizing | Try yourself |
| Senville | PC 02 | Compressor or IPM over-temperature protection | Ensure clear outdoor airflow & clean coil; repeats → tech | Try yourself |
| Senville | PC 04 | Inverter compressor drive error (legacy 'P4') | Technician — outdoor board, fan motor, or compressor | Call a pro |
| Gree | E1 | System high-pressure protection (dirty coil, blocked airflow, failed fan) | Off; clean the outdoor coil & clear airflow, restart | Try yourself |
| Gree | E2 | Indoor anti-freeze protection — coil too cold | Off; clean filter, clear airflow, let ice melt, restart | Try yourself |
| Gree | E3 | Compressor low-pressure protection (often a leak / low charge) | Technician — refrigerant work requires EPA 608 | Call a pro |
| Gree | E4 | Compressor discharge temperature too high | Technician — do not run; refrigerant or compressor problem | Call a pro |
| Gree | E5 | Low-voltage / over-current protection (unstable supply) | Confirm a correctly rated dedicated circuit & stable voltage | Try yourself |
| Gree | E6 | Communication malfunction between indoor & outdoor units | Power off at breaker ~1 min, restart; returns → tech | Try yourself |
| Gree | E8 | High-temperature (anti-high-temperature) protection | Off; clean filters, improve airflow, let it cool, restart | Try yourself |
| Gree | F0 | Refrigerant leak / lack-of-refrigerant protection | Technician — refrigerant work requires EPA 608 | Call a pro |
| Gree | F1 | Indoor evaporator (coil) temperature sensor fault | Technician — board/sensor diagnosis | Call a pro |
| Gree | F2 | Outdoor condenser coil temperature sensor fault | Technician | Call a pro |
| Gree | F3 | Outdoor ambient temperature sensor fault | Technician | Call a pro |
| Gree | F4 | Compressor discharge-tube temperature sensor fault | Technician | Call a pro |
| Gree | H1 | Defrost mode — normal status during heating, NOT a failure | Normal — wait a few minutes; heating resumes | Not a fault |
| Gree | H3 | Compressor overload protection tripped | Off; let it cool, ensure clean coil & airflow, restart | Try yourself |
| Gree | H5 | IPM (inverter power module) protection | Power off ~1 min and restart; returns → tech | Try yourself |
| Gree | H6 | No feedback from the indoor fan motor (blocked or faulty) | Off; check the indoor fan is not obstructed, restart | Try yourself |
| Gree | C5 | Jumper-cap / configuration fault or incompatible pairing | Technician — control-board/configuration issue | Call a pro |
| Gree | EE | EEPROM (control-board memory) malfunction | Technician — control board needs service | Call a pro |
| Pioneer | E0 | Indoor/outdoor communication fault (Diamante/WYT) | Power off ~3 min, restart; verify signal wires tight | Try yourself |
| Pioneer | E1 / EL 01 | Indoor room sensor fault — OR indoor/outdoor comms (varies by series) | Power-cycle; for comms, check the 4 low-voltage wires | Try yourself |
| Pioneer | E2 | Indoor coil (evaporator) temperature sensor fault | Power-cycle once; sensor replacement → technician | Call a pro |
| Pioneer | E3 | Outdoor coil temperature sensor fault | Power-cycle; sensor diagnosis → technician | Call a pro |
| Pioneer | E4 | System abnormality / general system fault | Power off several minutes, restart; returns → tech | Try yourself |
| Pioneer | E5 | Model configuration / setting mismatch | Technician — control-board configuration | Call a pro |
| Pioneer | E6 | Indoor fan motor fault | Confirm blower wheel not blocked, power-cycle | Try yourself |
| Pioneer | EC | Outdoor comms (Diamante/WYT) — OR refrigerant-leak detection (Quantum) | Power-cycle & check outdoor wiring. Leak → EPA 608 tech | Try yourself |
| Pioneer | E9 / P0 | IPM / inverter drive & module fault (possible failing compressor/board) | Technician — high-voltage inverter & compressor, not DIY | Call a pro |
| Pioneer | EE | EEPROM (control-board memory) fault | Power-cycle once; persists → technician (outdoor PCB) | Try yourself |
| Pioneer | EU | Voltage sensor fault | Verify a correctly rated dedicated circuit; then tech | Try yourself |
| Pioneer | EA | Current sensor fault | Technician — outdoor power board | Call a pro |
| Pioneer | CL | Air-filter cleaning reminder (NOT a malfunction) | Normal — clean the indoor filters, then power-cycle to clear | Not a fault |
| Pioneer | P1 | Over-voltage / under-voltage protection | Confirm stable power on a dedicated breaker; recurs → tech | Try yourself |
| Pioneer | P2 | Overcurrent protection | Technician — electrical/compressor load problem | Call a pro |
| Pioneer | P0 | Module (IPM hardware) protection — inverter power module | Technician — high-voltage inverter fault, not DIY | Call a pro |
| LG | CH01 | Indoor air (room) temperature sensor — open/short | Technician — sensor check | Call a pro |
| LG | CH02 | Indoor pipe (inlet) sensor — open/short | Technician — sensor check | Call a pro |
| LG | CH04 | Drain pump / float switch fault | Clear the condensate drain; persists → tech | Try yourself |
| LG | CH05 | Indoor ↔ outdoor communication error (often wiring) | Power-cycle; inspect connecting wiring | Try yourself |
| LG | CH06 | Indoor pipe (outlet) sensor fault | Technician — sensor | Call a pro |
| LG | CH07 | Indoor units set to conflicting modes (multi-split) | Set all indoor units to the same mode | Try yourself |
| LG | CH10 | Indoor fan (BLDC) motor locked | Clear obstructions; persists → technician | Try yourself |
| LG | CH21 | Compressor inverter (IPM) over-current | Power off — technician (compressor) | Call a pro |
| LG | CH22 | Compressor high current | Technician (compressor) | Call a pro |
| LG | CH23 | DC link low voltage | Technician — power supply | Call a pro |
| LG | CH26 | Compressor position / start fault | Technician (compressor) | Call a pro |
| LG | CH38 | Low refrigerant (leak) or unstable power | Technician — EPA 608, not DIY | Call a pro |
| LG | CH53 | Communication (indoor → outdoor signal) error | Power-cycle; check wiring; persists → tech | Try yourself |
| LG | CH67 | Outdoor fan motor locked | Clear debris around the outdoor fan; persists → tech | Try yourself |
No codes match that search. Try fewer characters, or pick your brand below and check its full guide.
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Prefer the full explanation for your manufacturer? Choose your brand for a lean quick-lookup table of codes, meanings, and safe first steps: