If your Toshiba high-wall air conditioner is showing unusual behaviour, flashing lights, or won’t operate as expected, it could be trying to tell you something. Toshiba air conditioning units come equipped with a self-diagnosis system that uses check codes to indicate faults.
This guide will help you understand how to use the remote control in service mode, interpret the codes, and determine the necessary next steps for repair or maintenance.
How to Use the Toshiba Remote Controller in Service Mode
Your Toshiba air conditioner allows you to access diagnostic codes using the remote control. Here’s how:
- Press the [CHECK] button with a pen or pencil to enter service mode. A “ ” icon appears on the display.
- Press the [ON] or [OFF] button to start the self-diagnosis process.
- The system will scan for up to 52 error codes. If no faults are found, the unit beeps once and the display changes.
- If a fault is detected:– The indoor unit beeps continuously for 10 seconds– All indicator lamps flash rapidly (5Hz)– A two-digit alphanumeric check code appears on the remote display
- Press [START/STOP] to exit service mode when done.
- To clear stored error codes, press [CLR] and send check code “7F”.
Press the [ON] or [OFF] button to start the self-diagnosis process.
The system will scan for up to 52 error codes. If no faults are found, the unit beeps once and the display changes.
If a fault is detected:
- – The indoor unit beeps continuously for 10 seconds
- – All indicator lamps flash rapidly (5Hz)
- – A two-digit alphanumeric check code appears on the remote display
– The indoor unit beeps continuously for 10 seconds
– All indicator lamps flash rapidly (5Hz)
– A two-digit alphanumeric check code appears on the remote display
Press [START/STOP] to exit service mode when done.
To clear stored error codes, press [CLR] and send check code “7F”.
Toshiba Air Conditioner Error Codes & Meaning
Here is a breakdown of common check codes and what each one indicates:
Indoor Unit Faults
| Fault | Cause | Action |
|---|---|---|
| Room Temperature Sensor Fault (TA) | Disconnected, short-circuit, or failure | Check and replace sensor or P.C. board |
| Heat Exchanger Sensor Fault (TC / TCj) | Disconnected, out of place, or faulty | Inspect placement, replace sensor or P.C. board |
| Indoor Fan Error | Fan motor fault or control board issue | Check motor operation and replace board if needed |
| General Indoor PCB Fault | Internal failure | Replace indoor P.C. board |
Outdoor Unit Faults
| Fault | Cause | Action |
|---|---|---|
| Outdoor Heat Exchanger Sensor (TE / TS) Fault | Short-circuit or disconnection | Check sensors and P.C. board |
| Discharge Temperature Sensor (TD) Fault | Faulty sensor or wiring | Inspect sensor; replace if damaged |
| Outdoor Fan System Error | Fan motor or drive system issue | Replace fan motor or P.C. board |
| Outdoor Temp Sensor (TO) Fault | Faulty reading | Check sensor and connections |
Electrical & Compressor Faults
| Fault | Cause | Action |
|---|---|---|
| Inverter Overcurrent | Short circuit or overload | Replace outdoor P.C. board |
| Position Detection Error | Fault in compressor windings | Replace compressor or control board |
| Compressor Does Not Start | Current not detected after startup | Check wiring or compressor |
| Compressor Drive Output Error | Severe internal fault | Check voltage, gas pressure, or replace compressor |
| High Discharge Temperature (>117°C) | Overload, gas leak, sensor fault | Check TD sensor, recharge gas, inspect P.M.V. |
| 4-Way Valve Inverse Fault | Heating error (TC sensor drop) | Check 4-way valve function |
Signal & Communication Errors
| Fault | Cause | Action |
|---|---|---|
| Serial Signal Not Returning | Wiring issue or gas shortage | Check cable connections, inverter board, and charge level |
| Serial Signal Stops Midway | Compressor or P.C. board issue | Replace relevant board or repair wiring |
For quick error code diagnosis, we’ve built a simple troubleshooting tool, just select your error code and instantly get the details you need.
Important Notes After Diagnosis
- Turn off the power supply after service and restart the system to reset temporary conditions.
- Permanent faults must be cleared manually using the remote (CLR → 7F).
- Errors stored in the system remain in memory until cleared — even after power loss.
Permanent faults must be cleared manually using the remote (CLR → 7F).
Errors stored in the system remain in memory until cleared — even after power loss.
Toshiba Offical Manual Link: https://www.toshiba-aircon.co.uk/assets/uploads/pdf/eoi/Fault_Diagnosis_From_Infa_Red_2.pdf
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Written by
Ali Elm
Ali is the Head of Operations at Be Cool Refrigeration with over a decade of hands-on experience in HVAC and commercial refrigeration. He oversees every installation, repair, and maintenance project, making sure the work meets the highest standards. Ali holds full F-Gas certification and has worked across residential, commercial, and industrial refrigeration systems throughout London and the South East. When he is not on site, he writes these guides to help business owners and homeowners understand their cooling systems better.