Toshiba VRF Systems — What You Need to Know
Toshiba VRF is branded as the SMMS series (SMMS-i, SMMS-e, SHRMe, Mini-SMMS). They use the TCC-Link (Toshiba Carrier Communication) proprietary 2-wire bus. Note: Toshiba Carrier is a joint venture — they share technology but use different fault code systems from Carrier.
- Codes display on the wired remote (RBC series), outdoor PCB LED, or via Toshiba T-CONNECT
- Format: P = protection, E = sensor/component, L = communication, F = system
- Strong in Australian commercial projects — particularly where simultaneous heating and cooling is needed (SHRMe)
Toshiba error codes use clear prefixes: P = protection/safety, E = sensor/component, L = communication, F = system/refrigerant. The prefix tells you the fault category immediately.
“Toshiba prefixes tell you the category instantly: P = protection, E = sensor, L = communication, F = system.”
Communication Faults (L Codes)
L03
Communication error between outdoor and indoor units
What it means
The outdoor unit has lost TCC-Link communication with one or more indoor units.
What to check first
Check 2-wire TCC-Link cable. Verify A/B polarity — TCC-Link IS polarity-sensitive. Measure communication voltage. Check for damaged wiring, water ingress, loose terminals.
Common cause
Reversed A/B polarity on one indoor unit. Damaged cable. Water ingress.
Nexus iQ advantage: Communication faults start intermittent. Nexus iQ logs every dropout with timestamp and unit ID.
↓ Back to searchL04
Communication error between outdoor units
What it means
In multi-outdoor systems, inter-unit communication has failed.
What to check first
Check inter-unit cable. Verify master/sub addressing. Check DIP switches.
↓ Back to searchL05
Communication error with wired remote controller
What it means
Wired remote has lost communication with indoor unit.
What to check first
Check connection. Verify address. Power cycle controller.
↓ Back to searchL06
Communication error with central controller
What it means
Central controller or BMS gateway lost communication.
What to check first
Check RS485 wiring. Verify addressing and baud rate. Check BMS gateway.
↓ Back to searchL08
Address setting error
What it means
Indoor unit address conflict or not configured.
What to check first
Verify all addresses are unique. Re-address via DIP switches or controller menu.
↓ Back to searchL10
Outdoor unit inter-board communication error
What it means
Internal communication failure between PCBs within the outdoor unit.
What to check first
Check ribbon cables between main PCB and inverter PCB. Check for corrosion, moisture. Check connectors.
↓ Back to searchProtection Faults (P Codes)
P01
High pressure protection
What it means
Discharge pressure exceeded high pressure switch setpoint.
What to check first
Check condenser coil for blockage. Verify condenser fan. Check refrigerant charge. Check outdoor ambient.
Common cause
Dirty condenser coil. Fan failure. Overcharge.
↓ Back to searchP02
Low pressure protection
What it means
Suction pressure dropped below minimum threshold.
What to check first
Check refrigerant charge. Look for restrictions. Check EEV. Check for ice on evaporator.
Common cause
Slow leak. Blocked filter drier.
↓ Back to searchP03
High discharge temperature protection
What it means
Compressor discharge temperature exceeded safe limit.
What to check first
Check refrigerant charge. Check condenser airflow. Verify EEV operation. Check for non-condensables.
Nexus iQ advantage: Discharge temperature trending up over weeks is the earliest warning. Nexus iQ catches it before P03 triggers.
↓ Back to search“Discharge temperature trending up over weeks is the earliest warning.”
P04
Compressor overcurrent protection
What it means
Inverter detected overcurrent on compressor motor.
What to check first
Check compressor insulation resistance. Check for liquid slugging. Check incoming voltage — all three phases.
Compressor replacement on a Toshiba SMMS: $8,000–$16,000.
↓ Back to searchP05
Inverter overcurrent (instantaneous)
What it means
Short-duration current spike on inverter output.
What to check first
Check compressor winding insulation. Check for short circuits. Check for moisture.
↓ Back to searchP07
Inverter IPM fault
What it means
Intelligent Power Module has detected a fault.
What to check first
Check IPM for damage. Check heatsink temp and fan. Check voltage quality. Module replacement if persistent.
↓ Back to searchP10
Inverter heatsink overtemperature
What it means
Inverter heatsink exceeded safe temperature.
What to check first
Check heatsink for dust. Verify heatsink fan. Check refrigerant charge — inverter is refrigerant-cooled on Toshiba.
A $200 heatsink cleaning prevents a $3,000 inverter module replacement.
↓ Back to search“A $200 heatsink cleaning prevents a $3,000 inverter module replacement.”
P12
Compressor startup failure
What it means
Compressor failed to start within expected time.
What to check first
Check wiring. Check for locked rotor. Verify crankcase heater. Try different mode.
Common cause
Liquid refrigerant migration to crankcase.
↓ Back to searchP13
Compressor over-speed protection
What it means
Compressor frequency exceeded maximum RPM.
What to check first
Check refrigerant charge. Check for restrictions.
↓ Back to searchP15
Phase reversal / Open phase
What it means
Incorrect phase sequence or phase loss.
What to check first
Check all three phases. Verify phase rotation. Check for single-phasing.
↓ Back to searchP16
Anti-freeze protection (indoor)
What it means
Indoor coil temperature dropped too low.
What to check first
Check indoor fan operation. Check air filter. Check refrigerant charge.
↓ Back to searchP17
DC bus overvoltage
What it means
DC link voltage inside inverter too high.
What to check first
Check incoming voltage for spikes. Check inverter board.
↓ Back to searchP18
DC bus undervoltage
What it means
DC link voltage too low.
What to check first
Check incoming voltage under load. Check capacitors.
↓ Back to searchP20
Outdoor unit overload
What it means
System operating beyond design capacity.
What to check first
Check capacity ratio. Verify indoor unit configuration.
↓ Back to searchP22
Oil recovery fault
What it means
Oil not returning to compressor.
What to check first
Check oil level. Verify oil recovery piping. Check refrigerant charge.
↓ Back to searchP25
Refrigerant overcharge
What it means
Excessive refrigerant detected.
What to check first
Check subcooling. Recover excess.
↓ Back to searchP26
Refrigerant undercharge
What it means
Insufficient refrigerant.
What to check first
Check for leaks. Add refrigerant.
↓ Back to searchStop chasing Toshiba fault codes.
Nexus iQ monitors discharge temperature, compressor frequency, and communication health 24/7.
See How It WorksSensor & Component Faults (E Codes)
E01
Indoor room temperature sensor fault
What it means
Return air sensor out of range or open circuit.
What to check first
Measure thermistor resistance (10kΩ at 25°C). Check connector. Check for damage.
Common cause
Sensor displaced during filter cleaning.
↓ Back to searchE02
Indoor pipe temperature sensor fault
What it means
Indoor coil sensor failed.
What to check first
Measure resistance. Check placement on evaporator coil.
↓ Back to searchE03
Indoor discharge sensor fault
What it means
Discharge air sensor failed.
What to check first
Measure resistance. Check placement.
↓ Back to searchE06
Indoor fan motor fault
What it means
Fan motor failed or feedback abnormal.
What to check first
Check motor resistance. Check obstruction. Check bearings. Check connector.
Common cause
Dust buildup. Bearing failure.
↓ Back to searchE07
Indoor EEV fault
What it means
Electronic expansion valve not responding.
What to check first
Check EEV coil resistance. Verify driver on PCB. Check wiring. Listen for EEV.
↓ Back to searchE09
Drain pump fault / Float switch
What it means
Condensate overflow or float switch activated.
What to check first
Clear drain line. Check float switch. Clean drain pan.
Common cause
Blocked drain. Kinked hose.
↓ Back to searchE14
Indoor PCB fault
What it means
Indoor control board internal error.
What to check first
Power cycle. Check voltage. PCB replacement if persistent.
↓ Back to searchE20
Outdoor air temperature sensor fault
What it means
Ambient sensor failed.
What to check first
Measure resistance. Check connector. Replace if open circuit.
↓ Back to searchE21
Discharge temperature sensor fault
What it means
Compressor discharge pipe sensor failed.
What to check first
Measure resistance. Check placement. Verify insulation.
↓ Back to searchE22
Suction temperature sensor fault
What it means
Suction pipe sensor out of range.
What to check first
Measure resistance. Check placement.
↓ Back to searchE23
Heat exchanger temperature sensor fault
What it means
Condenser coil sensor failed.
What to check first
Measure resistance. Check placement.
↓ Back to searchE25
CT sensor fault
What it means
Current transformer reading abnormal.
What to check first
Check CT clamp. Verify PCB connection.
↓ Back to searchE27
High pressure sensor fault
What it means
High pressure transducer reading abnormal.
What to check first
Verify with gauges. Check wiring. Replace sensor if faulty.
↓ Back to searchE28
Low pressure sensor fault
What it means
Low pressure transducer out of range.
What to check first
Same approach as E27 — verify with gauges, check wiring.
↓ Back to searchSystem Faults (F Codes)
F01
Four-way valve fault
What it means
Reversing valve not switching correctly.
What to check first
Check valve coil continuity. Listen for switching. Compare discharge/suction temps.
↓ Back to searchF03
Outdoor fan motor fault
What it means
Condenser fan motor failed or drawing excessive current.
What to check first
Check motor resistance. Check obstructions. Check bearings. Check connector.
↓ Back to searchF06
Outdoor PCB fault
What it means
Main outdoor control board internal error.
What to check first
Power cycle. Check voltage. PCB replacement if persistent.
↓ Back to searchF08
EEPROM fault
What it means
Memory chip read/write error.
What to check first
Full power cycle (2 minutes off). PCB replacement if persistent.
↓ Back to searchF10
Capacity code mismatch
What it means
Indoor/outdoor capacity configuration doesn’t match.
What to check first
Verify capacity code DIP settings. Recalculate combination ratio.
↓ Back to searchWhat Monitoring Catches
Toshiba fault codes tell you what’s broken. Monitoring tells you what’s about to break.
| WITHOUT MONITORING | WITH NEXUS iQ |
|---|---|
| Fault code → emergency callout | Trend → scheduled service |
| No history before fault | Full data: temps, pressures, Hz, runtime |
| Guessing which unit in an SMMS system | Nexus pinpoints exact unit |
| $2,000–$5,000 emergency callout | $200 preventive service |
| Compressor fails → $8,000–$16,000 | Stress caught early |
The most expensive fault code is the one you could have prevented.
Quick Reference Table
Use this searchable table to quickly find any Toshiba SMMS fault code.
| Code | Category | Description | Severity |
|---|---|---|---|
| L03 | Communication | Communication error — outdoor to indoor | Critical |
| L04 | Communication | Communication error — between outdoor units | Warning |
| L05 | Communication | Communication error — remote controller | Warning |
| L06 | Communication | Communication error — central controller | Warning |
| L08 | Communication | Address setting error | Info |
| L10 | Communication | Inter-board communication error | Critical |
| P01 | Refrigerant | High pressure protection | Critical |
| P02 | Refrigerant | Low pressure protection | Critical |
| P03 | Refrigerant | High discharge temperature | Critical |
| P04 | Compressor | Compressor overcurrent | Critical |
| P05 | Compressor | Inverter overcurrent (instantaneous) | Critical |
| P07 | Compressor | Inverter IPM fault | Critical |
| P10 | Compressor | Inverter heatsink overtemperature | Critical |
| P12 | Compressor | Compressor startup failure | Critical |
| P13 | Compressor | Compressor over-speed | Critical |
| P15 | System | Phase reversal / Open phase | Critical |
| P16 | Indoor | Anti-freeze protection | Warning |
| P17 | System | DC bus overvoltage | Critical |
| P18 | System | DC bus undervoltage | Critical |
| P20 | System | Outdoor unit overload | Warning |
| P22 | System | Oil recovery fault | Warning |
| P25 | Refrigerant | Refrigerant overcharge | Warning |
| P26 | Refrigerant | Refrigerant undercharge | Warning |
| E01 | Sensor | Indoor room temperature sensor | Warning |
| E02 | Sensor | Indoor pipe temperature sensor | Warning |
| E03 | Sensor | Indoor discharge sensor | Warning |
| E06 | Indoor | Indoor fan motor fault | Warning |
| E07 | Indoor | Indoor EEV fault | Warning |
| E09 | Indoor | Drain pump / Float switch | Warning |
| E14 | Indoor | Indoor PCB fault | Critical |
| E20 | Sensor | Outdoor air temperature sensor | Info |
| E21 | Sensor | Discharge temperature sensor | Warning |
| E22 | Sensor | Suction temperature sensor | Warning |
| E23 | Sensor | Heat exchanger sensor | Warning |
| E25 | Sensor | CT sensor fault | Warning |
| E27 | Sensor | High pressure sensor fault | Critical |
| E28 | Sensor | Low pressure sensor fault | Critical |
| F01 | System | Four-way valve fault | Warning |
| F03 | System | Outdoor fan motor fault | Warning |
| F06 | System | Outdoor PCB fault | Critical |
| F08 | System | EEPROM fault | Critical |
| F10 | System | Capacity code mismatch | Info |
Getting Started
Knowing what a fault code means is step one. Preventing it is step two.
1. Book a Demo
See Nexus iQ monitoring a live Toshiba SMMS system.
2. Connect Your System
Nexus 32 connects via Toshiba’s TCC-Link protocol. Under a day to install.
3. Stop Guessing
Within 24 hours you’ll have a complete diagnostic view. Within a month, predictive insights.