AC Error Codes · TOSOT
TOSOT AC Error Codes: What They Mean & What to Do
Find your code, understand what it means, then run a guided diagnosis.
Error Code Finder
Look a code up against sourced manufacturer records. Codes we cannot source are not listed — a guessed meaning is worse than no meaning.
TOSOT uses a four-letter code structure on its UNIX series split and inverter units. E codes are faults and protections on the unit itself, F codes are sensor faults, H codes are compressor and system protections, and P codes belong to the inverter driver board. One detail matters when reading the display: TOSOT documents upper-case EE and lower-case ee as two different faults.
How do TOSOT AC error codes work?
TOSOT E codes cover communication, freeze protection, overcurrent, discharge overheat and drain-pan alarms. F codes identify which temperature sensor failed — room, evaporator, outdoor ambient, condenser or defrost. H codes are compressor, IPM and overload protections. P codes report faults inside the inverter driver board, such as bus voltage and PFC protection.
Product families covered
-
UNIX series split / inverter
One consolidated E / F / H / P code table.
Where the code is displayed — and why it matters
The same fault can be labelled differently depending on which display you read it from, so identify the display before looking the code up.
- Indoor unit display
- Shows the code on the front panel display.
- Remote controller
- Some codes are read from the remote's display instead.
TOSOT code letters
The letter narrows the fault before you know the exact code:
- E
- Faults and protections on the unit — communication, freeze, overcurrent, drain
- F
- Temperature sensor faults (indoor, outdoor, coil, defrost)
- H
- Compressor, IPM and system protections
- P
- Inverter driver board faults — bus voltage, PFC, driver current
How the families differ
- Upper-case EE is an outdoor memory chip error while lower-case ee is a high-pressure sensor error — check the case on the display before looking either up.
- H1 is defrost mode, which is normal operation rather than a fault, so it should not be treated as a breakdown.
- TOSOT ducted, cassette and commercial line codes were not covered in our source material and are not published here.
Documented TOSOT UNIX series codes
From the official TOSOT UNIX user manual malfunction table, cross-validated against an independent technical breakdown. The source gives no severity column for TOSOT, so no severity level is published.
| Code | What it reports | Applies to | Severity | Source |
|---|---|---|---|---|
| E0 | Indicates indoor unit EEPROM / main PCB communication fault | UNIX series split / inverter | — | B |
| E1 | Indicates indoor–outdoor communication failure | UNIX series split / inverter | — | B |
| E2 | Indicates indoor evaporator coil freeze / anti-freeze protection | UNIX series split / inverter | — | B |
| E3 | Indicates outdoor fan or overcurrent protection / compressor overload | UNIX series split / inverter | — | B |
| E4 | Indicates high discharge temperature protection / compressor discharge overheat | UNIX series split / inverter | — | B |
| E5 | Indicates overcurrent protection / compressor overload trip | UNIX series split / inverter | — | B |
| E6 | Indicates indoor fan motor fault / DC fan motor feedback error | UNIX series split / inverter | — | B |
| E7 | Indicates mode conflict / reversing valve or indoor–outdoor mode mismatch | UNIX series split / inverter | — | B |
| E8 | Indicates high-pressure protection / overload protection | UNIX series split / inverter | — | B |
| E9 | Indicates water overflow protection / full drain pan alarm | UNIX series split / inverter | — | B |
| EE | Indicates outdoor unit memory chip error | UNIX series split / inverter | — | B |
| ee | Indicates high-pressure sensor error | UNIX series split / inverter | — | B |
| F0 | Indicates low refrigerant / refrigerant leakage protection | UNIX series split / inverter | — | B |
| F1 | Indicates indoor ambient (room) temperature sensor fault | UNIX series split / inverter | — | B |
| F2 | Indicates indoor evaporator temperature sensor fault | UNIX series split / inverter | — | B |
| F3 | Indicates outdoor ambient temperature sensor fault | UNIX series split / inverter | — | B |
| F4 | Indicates outdoor condenser coil temperature sensor fault | UNIX series split / inverter | — | B |
| F5 | Indicates defrost temperature sensor / outdoor coil sensor fault | UNIX series split / inverter | — | B |
| F6 | Indicates compressor low-frequency protection / inverter drive capacity mismatch or frequency restriction | UNIX series split / inverter | — | B |
| F8 | Indicates indoor fan speed out of control / feedback error | UNIX series split / inverter | — | B |
| F9 | Indicates indoor coil outlet temperature sensor fault | UNIX series split / inverter | — | B |
| H0 | Indicates indoor PCB EEPROM parameter error | UNIX series split / inverter | — | B |
| H1 | Indicates defrost mode active | UNIX series split / inverter | — | B |
| H2 | Indicates compressor overheat protection in heating | UNIX series split / inverter | — | B |
| H3 | Indicates compressor overload protection / overheat | UNIX series split / inverter | — | B |
| H4 | Indicates indoor–outdoor mismatch / EEPROM compatibility error | UNIX series split / inverter | — | B |
| H5 | Indicates iPM protection / inverter module fault | UNIX series split / inverter | — | B |
| H6 | Indicates outdoor fan motor fault | UNIX series split / inverter | — | B |
| H7 | Indicates compressor position protection / inverter startup fault | UNIX series split / inverter | — | B |
| H8 | Indicates water leakage protection (some models) | UNIX series split / inverter | — | B |
| H9 | Indicates indoor coil low-temperature protection in heating | UNIX series split / inverter | — | B |
| Lc | Indicates startup failure | UNIX series split / inverter | — | B |
| P0 | Indicates driver reset protection | UNIX series split / inverter | — | B |
| P5 | Indicates pFC protection | UNIX series split / inverter | — | B |
| P6 | Indicates driver module sensor error | UNIX series split / inverter | — | B |
| P7 | Indicates driver module high-temperature protection | UNIX series split / inverter | — | B |
| P8 | Indicates aC current protection | UNIX series split / inverter | — | B |
| PA | Indicates driver current error | UNIX series split / inverter | — | B |
| Pc | Indicates bus low-voltage protection | UNIX series split / inverter | — | B |
| PL | Indicates bus high-voltage protection | UNIX series split / inverter | — | B |
| PH | Indicates charge loop error | UNIX series split / inverter | — | B |
| PU | Indicates drive memory chip error | UNIX series split / inverter | — | B |
Before you act on a code
- P-series codes report inverter driver board faults — leave the unit off rather than power-cycling repeatedly.
- E9 and H8 report water and drain-pan alarms: continuing to run the unit risks water damage to ceilings and finishes.
- TOSOT ducted, cassette and commercial code tables are still in technical review.
Corroborated across independent technical sources
How to identify your system
- Note the code exactly as displayed, including whether the letters are upper or lower case.
- Note whether the code appeared on the indoor unit display or the remote.
- Photograph the indoor unit's model label before contacting a technician.
No code showing? Start from the symptom
TOSOT error codes — common questions
What does TOSOT E1 mean?
E1 is an indoor–outdoor communication failure. The cooling circuit may be perfectly healthy; the fault lies in the interconnecting wiring, the terminations or the boards at either end. One power cycle is reasonable, but a code that returns needs inspection.
Is TOSOT H1 a fault?
No. H1 indicates defrost mode is active, which is normal operation. If the unit is not cooling while H1 is shown, wait for the cycle to finish before treating it as a fault.
What does TOSOT F0 mean?
F0 is low refrigerant or refrigerant leakage protection. The system stopped to protect the compressor. Refrigerant work requires a technician with gauges — topping up without finding the leak simply repeats the failure.
Why does my TOSOT show E9?
E9 is water overflow protection — the drain pan is full. In Dubai this is usually a blocked or poorly sloped condensate drain, and it should be cleared promptly to avoid water damage.
Need this looked at properly?
Call or send a photo on WhatsApp and we will tell you whether it needs an inspection, and what the work involves, before anyone travels.
Sources consulted
- Official TOSOT UNIX 18 SEER user manual malfunction table
- Independent TOSOT technical breakdown with matching descriptions (cross-validation)