FoxESS inverter & battery fault codes explained
FoxESS H1(G2) hybrid and AC1(G2) AC-coupled inverters show a short fault name (for example Grid Lost Fault or Iso Fault) on the screen and in the FoxESS app. Battery problems appear as BMS messages. Find your message below.
Safety first, please read
- Solar panels and batteries produce dangerous DC voltage whenever there is daylight or charge in the battery, even with the mains switched off. Electrical work on these systems must only be done by a licensed electrician.
- Never open the inverter or battery, and don't unplug, touch or adjust DC cables, connectors or isolators except for the owner shutdown steps in your manufacturer's manual.
- For an isolation/insulation fault, earth fault, arc fault, residual-current fault or battery over-temperature alarm, or any smoke, burning smell, hissing, swelling, leaking or water damage: only switch off if the manufacturer's procedure lets you do it safely, keep everyone clear, and call a licensed electrician or Total Solar.
- If there is fire or smoke, get everyone out and call 000. Tell the fire service there is a solar and battery system on site.
- Don't climb on the roof to check or clean panels. Do checks from the ground only.
Owner shutdown and restart (FoxESS)
FoxESS's H1(G2) AU manual says to switch the inverter off by setting START/STOP to "stop" in the settings menu, then turning off the PV/DC switch, AC breaker, EPS breaker and battery breaker, and waiting 5 minutes before any work. Only do this if your installer has shown you how and it is safe.
H1(G2)/AC1(G2) hybrid & AC-coupled (AU) (47 codes)
Grid Lost FaultGrid is lostWarning
What it means: The inverter cannot see a normal mains supply, so it has stopped exporting to the grid (and a hybrid system may switch to backup).
Likely causes:
- Power outage in your street or area
- A tripped or switched-off solar/inverter circuit breaker in the switchboard
- Loose AC connection between the switchboard and the inverter
What you can safely do:
- Check whether the rest of the house (or your neighbours) has power, and check your network operator's outage map
- Check the switchboard for a tripped solar supply main switch or inverter breaker. Only reset it once. If it trips again, leave it off and call an electrician
- Wait. Once normal grid power is back, the inverter normally reconnects by itself after its safety checks (often a few minutes)
- If grid power is normal but the alarm stays, call us
Grid Volt FaultGrid voltage out of rangeWarning
What it means: The mains voltage the inverter measured was outside the limits allowed for your network, so it disconnected or reduced output to protect the grid. This is usually a grid condition, not a faulty inverter.
Likely causes:
- High street voltage, common on sunny afternoons when many homes export solar
- Grid disturbances or voltage dips
- Long or undersized AC cabling between the inverter and the switchboard (installation issue)
- Grid protection settings that don't match your network's requirements
What you can safely do:
- Wait. The inverter reconnects by itself once voltage is back within limits
- Note the time of day it happens. If it happens most sunny days, tell us, because it may need a voltage check or a report to your network operator
- Don't try to change grid protection settings yourself. In Australia they are set to AS/NZS 4777.2 and your network operator's requirements
Grid Freq FaultGrid frequency out of rangeWarning
What it means: Grid frequency moved outside the allowed range, so the inverter disconnected or reduced output as the standards require.
Likely causes:
- Short grid disturbance
- Running on a generator or a weak supply
- Grid settings that don't match the local network
What you can safely do:
- Wait for automatic reconnection
- If it happens often, record the times and contact us
10min Volt Fault10-minute average grid voltage out of rangeWarning
What it means: The mains voltage the inverter measured was outside the limits allowed for your network, so it disconnected or reduced output to protect the grid. This is usually a grid condition, not a faulty inverter.
Likely causes:
- High street voltage, common on sunny afternoons when many homes export solar
- Grid disturbances or voltage dips
- Long or undersized AC cabling between the inverter and the switchboard (installation issue)
- Grid protection settings that don't match your network's requirements
What you can safely do:
- Wait. The inverter reconnects by itself once voltage is back within limits
- Note the time of day it happens. If it happens most sunny days, tell us, because it may need a voltage check or a report to your network operator
- Don't try to change grid protection settings yourself. In Australia they are set to AS/NZS 4777.2 and your network operator's requirements
SW Inv Cur FaultOutput current high (software)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
DCI FaultDC component in output current out of limitFault
What it means: The inverter detected too much DC current in its AC output, which the grid standards don't allow, so it disconnected.
Likely causes:
- A one-off disturbance (if it is occasional)
- Internal measuring or power stage problem (if it repeats)
What you can safely do:
- If it happened once and the system recovered, keep an eye on it
- If it repeats, call us
HW Inv Cur FaultOutput current high (hardware)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
SW Bus Vol FaultBus voltage out of range (software)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Bat Volt FaultBattery voltage faultFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
SW Bat Cur FaultBattery current high (software)Fault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
Iso FaultIsolation (insulation) failedSafety-critical
What it means: The inverter's insulation check failed. FoxESS states this is how the earth fault alarm (IEC 62109-2 cl. 13.9) appears on this model: the screen shows the isolation fault and the red LED lights.
Likely causes:
- Damaged DC cable insulation (for example from rodents, UV or a pinched cable)
- Water in a DC connector, isolator or junction box
- A damaged solar panel or backsheet
- Heavy dew or rain can trigger it temporarily on marginal systems
What you can safely do:
- Do not touch panels, DC cables, rooftop isolators or the inverter's DC connectors
- If it clears by itself after the weather dries out, still report it, because repeated alarms point to a developing fault
- Book an electrician or call us. An insulation test needs specialist equipment
- If you see smoke, burn marks or smell burning, keep clear and call 000
Res Cur FaultResidual current highSafety-critical
What it means: The inverter measured leakage (residual) current flowing to earth above its safety limit and disconnected. This can indicate damaged insulation somewhere in the system.
Likely causes:
- Damaged DC or AC cable insulation
- Moisture in connectors or equipment
- A one-off disturbance (if it happens once and never again)
What you can safely do:
- Don't touch cabling or equipment
- If it happens repeatedly, or together with an insulation/isolation alarm, call an electrician or us promptly
Pv Volt FaultPV voltage out of rangeFault
What it means: The DC voltage coming from the solar panels is higher than the inverter is rated for. Over-voltage can damage the inverter.
Likely causes:
- Too many panels wired in series in a string (system design/installation issue)
- Very cold, bright mornings raise panel voltage
- Incorrect panel or string configuration after a change to the system
What you can safely do:
- Do not touch the DC isolator or cables unless the manufacturer's owner shutdown tells you to
- Call us. The string design needs to be checked by a licensed installer
SW Pv Cur FaultPV input current high (software)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Temp FaultInverter temperature highWarning
What it means: The inverter is running too hot, so it has reduced output or paused to protect itself.
Likely causes:
- High ambient temperature or direct afternoon sun on the inverter
- Blocked air vents or heat sink (dust, cobwebs, stored items)
- A fan problem (on fan-cooled models)
What you can safely do:
- Make sure nothing is stacked against or in front of the inverter, and leave the manufacturer's clearances around it
- Gently clear dust or leaves from the outside of the vents, without opening the unit or spraying water
- Let it cool. It normally resumes by itself
- If it keeps happening on mild days, call us
Ground FaultGround connection failedSafety-critical
What it means: The inverter detected a problem with the earth (protective earth/PE) or with the neutral-to-earth connection. A sound earth is essential for electrical safety.
Likely causes:
- Loose or missing earth connection on the inverter or array
- Neutral and earth problem in the AC wiring or switchboard
- Fault in the building's main earth
What you can safely do:
- Do not touch the inverter, frames or cabling
- Leave the system off if it has shut down. Call a licensed electrician or us to test the earthing
Over Load FaultOverload in on-grid modeWarning
What it means: The backup/EPS (off-grid) output is overloaded or abnormal, so the system has limited or switched off backup power.
Likely causes:
- Too many or too large appliances on backup circuits during an outage (for example ovens, air conditioners, pumps)
- High start-up surge from motors or compressors
- A short circuit on a backup circuit
What you can safely do:
- Switch off large appliances on backup circuits
- Wait for the system to retry (some models lock out for a period after repeated overloads)
- If it trips with only small loads on, or you suspect a short circuit, call an electrician
Eps Over LoadOverload in off-grid (EPS) modeWarning
What it means: The backup/EPS (off-grid) output is overloaded or abnormal, so the system has limited or switched off backup power.
Likely causes:
- Too many or too large appliances on backup circuits during an outage (for example ovens, air conditioners, pumps)
- High start-up surge from motors or compressors
- A short circuit on a backup circuit
What you can safely do:
- Switch off large appliances on backup circuits
- Wait for the system to retry (some models lock out for a period after repeated overloads)
- If it trips with only small loads on, or you suspect a short circuit, call an electrician
Bat Power LowBattery power lowInfo
What it means: The battery's state of charge or voltage is low, so the system has stopped discharging it to protect the cells.
Likely causes:
- Battery has been used down to its reserve level
- Several cloudy days with little solar to recharge
- Charging is disabled by the settings or by another fault
What you can safely do:
- Allow it to recharge from solar (or the grid, if your settings allow)
- Check the app for other alarms that could be stopping charging
- If it stays low for days in good sun, call us. Batteries left flat for long periods can be damaged
HW Bus Vol FaultBus voltage out of range (hardware)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
HW Pv Cur FaultPV input current high (hardware)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
HW Bat Cur FaultBattery current high (hardware)Fault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
SCI FaultMaster-manager communication failedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
MDSP SPI FaultMaster-slave communication failedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
MDSP Smpl FaultMaster sample detection circuit failedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Res Cur HW FaultResidual current detection device failedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Inv EEPROM FaultInverter EEPROM faultFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
PvCon Dir FaultPV connection reversedFault
What it means: A solar string or the battery appears to be connected with positive and negative swapped.
Likely causes:
- Polarity error during installation or maintenance
What you can safely do:
- Do not touch any DC wiring
- Call us or a licensed electrician
Bat Relay OpenBattery relay stays openFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
Bat Relay Short CircuitBattery relay stays closedFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
Bat Buck FaultBattery buck circuit MOSFET failedFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
Bat Boost FaultBattery boost circuit MOSFET failedFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery or touch its terminals
- Note the exact alarm text and time from the app
- Call us. Battery faults should be handled by the installer or manufacturer
Eps Relay FaultEPS relay failedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
BatCon Dir FaultBattery connection reversedFault
What it means: A solar string or the battery appears to be connected with positive and negative swapped.
Likely causes:
- Polarity error during installation or maintenance
What you can safely do:
- Do not touch any DC wiring
- Call us or a licensed electrician
Main Relay OpenGrid relay stays openFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
S1 Close FaultGrid relay S1 stays closedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
S2 Close FaultGrid relay S2 stays closedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
M1 Close FaultGrid relay M1 stays closedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
M2 Close FaultGrid relay M2 stays closedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
GridV Cons FaultGrid voltage sample mismatch (master/slave)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
GridF Cons FaultGrid frequency sample mismatch (master/slave)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Dci Cons FaultDCI sample mismatch (master/slave)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Rc Cons FaultResidual current sample mismatch (master/slave)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
RDSP SPI FaultMaster-slave communication failed (RDSP)Fault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
RDSP Smpl FaultSlave sample detection circuit failedFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
ARM EEPROM FaultManager EEPROM faultFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Note the code, time and whether it clears by itself
- If your installer showed you the owner shutdown/restart procedure from the manufacturer's manual (summarised at the top of this page), you may restart the system once. Do not open covers or touch cabling.
- If the code returns or the system stays offline, call us. Internal faults are a warranty/technician job
Meter Lost FaultMeter communication interruptedWarning
What it means: The inverter isn't getting correct readings from its energy meter or current sensor (CT). This affects export limiting, battery charging and monitoring accuracy.
Likely causes:
- Meter or CT communication cable loose or damaged
- CT clamp fitted on the wrong cable or the wrong way round
- Meter has lost power or is faulty
What you can safely do:
- Check the app. Generation may still be running normally
- Don't open the switchboard
- Call us to check the meter/CT wiring. If your system has an export limit, this needs fixing promptly
H1(G2)/AC1(G2) hybrid & AC-coupled — battery (BMS) alarms (23 codes)
BMS LostBMS communication interruptedFault
What it means: The inverter and battery (or parts inside the battery) have stopped talking to each other, so the battery may stop charging or discharging.
Likely causes:
- Battery switched off or in a protection state
- Loose or damaged communication cable
- Firmware or settings mismatch
What you can safely do:
- Check the battery's indicator lights and your monitoring app for other alarms
- Don't unplug or re-plug cables yourself
- Call us if it does not clear within a few hours
BMS Ext FaultBMS external communication interruptedFault
What it means: The inverter and battery (or parts inside the battery) have stopped talking to each other, so the battery may stop charging or discharging.
Likely causes:
- Battery switched off or in a protection state
- Loose or damaged communication cable
- Firmware or settings mismatch
What you can safely do:
- Check the battery's indicator lights and your monitoring app for other alarms
- Don't unplug or re-plug cables yourself
- Call us if it does not clear within a few hours
BMS Int FaultCommunication between battery packs interrupted (or DIP switch wrong)Fault
What it means: The inverter and battery (or parts inside the battery) have stopped talking to each other, so the battery may stop charging or discharging.
Likely causes:
- Battery switched off or in a protection state
- Loose or damaged communication cable
- Firmware or settings mismatch
What you can safely do:
- Check the battery's indicator lights and your monitoring app for other alarms
- Don't unplug or re-plug cables yourself
- Call us if it does not clear within a few hours
BMS Volt HighBattery over-voltageFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Volt LowBattery under-voltageFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS ChgCur HighBattery charge over-currentFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS DchgCur HighBattery discharge over-currentFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Temp HighBattery over-temperatureSafety-critical
What it means: The battery (or one of its internal parts) is above its safe temperature, so charging or discharging is limited or stopped to protect it.
Likely causes:
- High ambient temperature or direct sun on the battery
- Poor ventilation around the battery
- Heavy charge/discharge loads
- An internal battery fault
What you can safely do:
- Keep clear and do not open or touch the battery
- If you notice smoke, a burning or chemical smell, hissing, swelling or leaking, leave the area, keep others away and call 000
- Otherwise, make sure the space around the battery is clear and shaded, and call us or a licensed electrician to check it
BMS Temp LowBattery under-temperatureWarning
What it means: The battery is too cold to charge or discharge safely, so it is pausing until it warms up.
Likely causes:
- Cold overnight or winter temperatures where the battery is installed
What you can safely do:
- Wait for the battery to warm up. Most systems recover automatically
- If it happens often, ask us whether the location or a heating feature (where the model has one) should be reviewed
BMS CellImbalanceCell capacity imbalanceFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS HW ProtectBattery hardware protectionFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Circuit FaultBMS hardware circuit faultFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Insul FaultBattery insulation faultSafety-critical
What it means: The inverter measured low insulation resistance between the solar/battery DC circuits and earth. In Australia this is treated as an earth fault alarm, and the system must be checked by a licensed electrician.
Likely causes:
- Damaged DC cable insulation (for example from rodents, UV or a pinched cable)
- Water in a DC connector, isolator or junction box
- A damaged solar panel or backsheet
- Heavy dew or rain can trigger it temporarily on marginal systems
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS VoltsSen FaultBattery voltage sensor faultFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS TempSen FaultBattery temperature sensor faultFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS CurSen FaultBattery current sensor faultFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Relay FaultBattery relay faultFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Type UnmatchBattery pack capacities differFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Ver UnmatchBattery slave software versions differFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS Mfg UnmatchCell manufacturer differsFault
What it means: The battery management system has reported a problem with battery voltage, current, cells or internal hardware and has limited or stopped battery operation.
Likely causes:
- Cell voltage or capacity imbalance
- Over-charge or over-discharge conditions
- Internal battery hardware (relay, sensor, circuit board) fault
- Firmware or configuration mismatch between battery modules
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS SwHw UnmatchSlave software/hardware mismatchFault
What it means: There is a firmware, model or configuration mismatch between parts of the system, so it can't run normally.
Likely causes:
- Interrupted or partial firmware update
- Parts replaced with different firmware versions
- Incorrect model or country/region setting
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS M&S UnmatchMaster/slave software mismatchFault
What it means: There is a firmware, model or configuration mismatch between parts of the system, so it can't run normally.
Likely causes:
- Interrupted or partial firmware update
- Parts replaced with different firmware versions
- Incorrect model or country/region setting
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
BMS ChgReq NoAckNo response to charge requestFault
What it means: The equipment's self-checks found an internal problem (for example relays, measuring circuits, internal communication or power electronics). Some of these clear by themselves after a one-off event, but repeated alarms usually need a technician.
Likely causes:
- A one-off disturbance (for example a grid event)
- Internal component or circuit board fault
- Firmware issue
What you can safely do:
- Do not open the battery
- Note the alarm and time
- Call us. FoxESS directs these to the battery supplier (your installer)
Manufacturer support contacts
| Contact | Phone | Email / channel |
|---|---|---|
| FoxESS Australia service (website) | 1300 377 369 or +61 7 3113 9965 | service.au@fox-ess.com |
If Total Solar installed your system, contact us first.
Need help with a fault code?
Book a service call with our licensed electricians, or call us to talk it through. Have your fault code and a photo of the screen or app ready.