Where do these FoxESS fault codes come from?

Compiled from publicly available FoxESS inverter and battery documentation and field references, then rewritten for the trade. Wattbench is independent and not affiliated with FoxESS.

Which of these can I clear on site?

Some clear on their own once grid or environmental conditions return to normal. Anything involving DC isolation, AC switching, wiring or opening the unit is licensed electrical work. Isolate safely, follow AS/NZS 5033 and AS/NZS 3000 procedure and use appropriate PPE before touching a live system.

The exact code isn't listed. Why not?

Firmware and model variants differ, and manufacturers revise their code tables. We document the most common ones; for a variant that isn't here, check the unit's current manual or the manufacturer's service portal.

How current is this reference?

This reference was last reviewed on 2 August 2026. We revise entries when the underlying manufacturer documentation changes.

Inverter Fault Library

FoxESS Inverter Error Codes

FoxESS hybrid and R-series alarms with separate owner-safe checks and source-linked installer remedies.

Sources listedReviewed August 2026Source: Manufacturer documentationOur methodology

Manufacturer: FoxESS (H1/AC1 hybrid inverters and R-series three-phase string inverters)
Codes documented: 48
Source: Manufacturer documentation
Scope: Reference only

48 of 48 codes

About this fault librarySources · scope

FoxESS uses two distinct fault-naming conventions across its range. The hybrid inverters (H1/AC1, including the G2 generation) report named text alarms such as `Grid Lost Fault`, `Bat Volt Fault` and `BMS Lost`, shown on the inverter panel or in FoxCloud. The R-series three-phase string inverters (R75/R100/R110) use numeric fault codes in the 1030–1345 range. Every code below is taken verbatim from FoxESS's own user manuals (the H1(G2)/AC1(G2) Manual V1.0.8 and the R-Series User Manual), with the legacy numeric grid codes (1, 26, 27, 28) corroborated against the FoxESS owners' community forum. Always confirm the exact wording on your own unit's display or in FoxCloud, as alarm sets vary by model and firmware.

Key takeaways

48 FoxESS (H1/AC1 hybrid inverters and R-series three-phase string inverters) fault and alarm codes, documented for the trade.
Compiled from published documentation and field references; Wattbench is independent and not affiliated with FoxESS (H1/AC1 hybrid inverters and R-series three-phase string inverters).
Codes involving DC/AC isolation, wiring or opening the unit are licensed electrical work. Isolate safely and follow AS/NZS procedure.

Resolution text is manufacturer/service context, not permission for an owner to perform electrical work. Stop at visible observations unless the exact product instructions identify an owner control. Isolation, configuration, testing, opening equipment and wiring are for an appropriately licensed worker and, where required, an SAA-accredited person. Where a card says Product fit is unknown, treat it as brand-level guidance and confirm the exact model, role, regional variant, firmware and current manual before acting.

Grid Lost Fault
Grid Lost Fault
The grid supply has been lost / disconnected, so the inverter has isolated from the grid. Often appears alongside grid voltage/frequency faults, frequently caused by a tripped breaker.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Grid Lost Fault: Grid Lost Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Grid Volt Fault
Grid Voltage Fault
Measured grid voltage is outside the allowed operating range (over- or under-voltage).
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Grid Volt Fault: Grid Voltage Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Grid Freq Fault
Grid Frequency Fault
Grid frequency is outside the allowed operating range.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Grid Freq Fault: Grid Frequency Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
10min Volt Fault
10-Minute Average Grid Voltage Fault
The 10-minute average grid voltage has been out of range, a regulatory over-voltage protection.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 10min Volt Fault: 10-Minute Average Grid Voltage Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bat Volt Fault
Battery Voltage Fault
Battery voltage is outside the inverter's normal operating range.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bat Volt Fault: Battery Voltage Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Check battery input voltage against the exact inverter and battery operating limits, then follow the battery supplier and FoxESS service path if it remains out of range.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Pv Volt Fault
PV Voltage Fault
PV (solar) input voltage is outside the allowed range.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Pv Volt Fault: PV Voltage Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Leave the inverter and PV wiring alone, record the alarm and contact your installer. Do not reset the inverter or operate isolators to test whether it clears.
Installer remedy
Measure the PV input under the approved procedure and compare it with the exact model limits and temperature-corrected string design. Correct the input condition before reconnection.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Iso Fault
Isolation (Insulation) Fault
Isolation/insulation resistance to ground has failed, typically from damaged cable insulation or moisture.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Iso Fault: Isolation (Insulation) Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and weather conditions. Do not reset the inverter, touch cables or operate isolators; arrange a licensed inspection if it persists or returns.
Installer remedy
Test the affected AC/DC insulation and earthing under the approved safe-isolation procedure. Locate damaged wiring, moisture ingress or an abnormal earth path before returning the system to service.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Res Cur Fault
Residual Current Fault
Detected residual (leakage) current is too high, often from damaged insulation.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Res Cur Fault: Residual Current Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and weather conditions. Do not reset the inverter, touch cables or operate isolators; arrange a licensed inspection if it persists or returns.
Installer remedy
Test the affected AC/DC insulation and earthing under the approved safe-isolation procedure. Locate damaged wiring, moisture ingress or an abnormal earth path before returning the system to service.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
DCI Fault
DCI (DC Injection) Fault
The DC component in the AC output current exceeds the permitted limit.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for DCI Fault: DCI (DC Injection) Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Follow the model-specific controlled disconnection and reconnection sequence once. If the fault returns, preserve the alarm record and escalate to FoxESS rather than repeatedly resetting it.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
SW Inv Cur Fault
Software Inverter Current Fault
Output current detected as too high by the software protection.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for SW Inv Cur Fault: Software Inverter Current Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Follow the model-specific controlled disconnection and reconnection sequence once. If the fault returns, preserve the alarm record and escalate to FoxESS rather than repeatedly resetting it.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
HW Inv Cur Fault
Hardware Inverter Current Fault
Output current detected as too high by the hardware protection.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for HW Inv Cur Fault: Hardware Inverter Current Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Follow the model-specific controlled disconnection and reconnection sequence once. If the fault returns, preserve the alarm record and escalate to FoxESS rather than repeatedly resetting it.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Temp Fault
Over-Temperature Fault
The inverter internal/ambient temperature is too high.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Temp Fault: Over-Temperature Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
From a safe position, keep the area around the inverter clear and note whether it is in direct sun or unusually hot. Do not open the unit; contact your installer if it does not recover after cooling.
Installer remedy
Check ambient conditions, clearances and ventilation against the installation manual. If conditions are compliant and the alarm remains, follow the FoxESS service path.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Ground Fault
Ground Connection Fault
The ground (PE) connection has failed.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Ground Fault: Ground Connection Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Do not reset the inverter or touch electrical equipment. Record the alarm and arrange a licensed electrician or your installer to attend.
Installer remedy
Check neutral-to-earth voltage, protective-earth continuity and AC wiring under the approved safe-isolation procedure, then follow the model restart sequence only after the fault is rectified.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Over Load Fault
Overload Fault (On-Grid)
The connected load exceeds the inverter's limit while in on-grid mode.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Over Load Fault: Overload Fault (On-Grid)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Switch off non-essential plug-in appliances and record which loads were operating when the alarm appeared. Contact your installer if the alarm remains under ordinary load.
Installer remedy
Compare the connected on-grid load with the model limit and investigate the load condition before following the product recovery procedure.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Eps Over Load
EPS Overload (Off-Grid)
The connected backup/EPS load exceeds the inverter's limit while in off-grid mode.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Eps Over Load: EPS Overload (Off-Grid)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Switch off non-essential plug-in appliances on the backup circuits and record which loads were operating. Contact your installer if backup does not recover.
Installer remedy
Compare the EPS load and starting demand with the commissioned backup limits, correct the load condition and verify recovery under the product procedure.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bat Power Low
Battery Power Low
The battery state of charge / available power is low.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bat Power Low: Battery Power Low
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Allow the battery time to recharge and avoid adding unnecessary backup loads. Contact your installer if the warning remains after charging conditions return.
Installer remedy
Confirm battery availability, state of charge and the commissioned operating settings. Follow the battery supplier and FoxESS path if the battery does not recover.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
PvCon Dir Fault
PV Connection Reversed
The PV string polarity is connected the wrong way round.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for PvCon Dir Fault: PV Connection Reversed
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Do not touch PV cables or connectors. Record the alarm and contact your installer before the system is operated again.
Installer remedy
Under approved safe isolation, verify and correct the affected PV input polarity before reconnection.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
BatCon Dir Fault
Battery Connection Reversed
The battery polarity is connected the wrong way round.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for BatCon Dir Fault: Battery Connection Reversed
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Do not touch battery cables or connectors. Record the alarm and contact your installer before the system is operated again.
Installer remedy
Under the battery and inverter safe-isolation procedures, verify and correct the battery polarity before reconnection.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Meter Lost Fault
Meter Communication Lost
Communication between the energy meter and the inverter has been interrupted.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Meter Lost Fault: Meter Communication Lost
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Verify the meter-to-inverter communication cable, termination and configured meter path under the installation manual. Restore the connection before testing export-control operation.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
BMS Lost
BMS Communication Lost
Communication between the battery BMS and the inverter has been interrupted.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for BMS Lost: BMS Communication Lost
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Verify the battery BMS communication cable, protocol and connection under the exact battery/inverter instructions. Escalate if communications do not recover.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms Int Fault
BMS Internal Fault
DIP switch in the wrong position, or communication between battery packs is interrupted.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms Int Fault: BMS Internal Fault
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Check the documented battery DIP-switch positions and inter-pack communication cables against the exact battery configuration, then follow the battery supplier path if the fault remains.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms Volt High
Battery Over-Voltage (BMS)
The battery BMS reports an over-voltage condition.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms Volt High: Battery Over-Voltage (BMS)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Preserve the BMS alarm data and follow the battery supplier's authorised diagnostic process; do not bypass the BMS or alter protection limits.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms Volt Low
Battery Under-Voltage (BMS)
The battery BMS reports an under-voltage condition.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms Volt Low: Battery Under-Voltage (BMS)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Preserve the BMS alarm data and follow the battery supplier's authorised diagnostic process; do not bypass the BMS or alter protection limits.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms ChgCur High
Battery Charge Over-Current (BMS)
The battery BMS reports a charge over-current.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms ChgCur High: Battery Charge Over-Current (BMS)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Preserve the BMS alarm data and follow the battery supplier's authorised diagnostic process; do not bypass the BMS or alter current limits.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms DchgCur High
Battery Discharge Over-Current (BMS)
The battery BMS reports a discharge over-current.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms DchgCur High: Battery Discharge Over-Current (BMS)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Preserve the BMS alarm data and follow the battery supplier's authorised diagnostic process; do not bypass the BMS or alter current limits.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms Temp High
Battery Over-Temperature (BMS)
The battery BMS reports an over-temperature condition.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms Temp High: Battery Over-Temperature (BMS)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Keep clear of the battery, record the alarm and contact your installer or battery supplier promptly. Do not open equipment, operate isolators or attempt a reset.
Installer remedy
Preserve the BMS alarm and temperature context, keep the battery out of service under the authorised procedure, and follow the battery supplier's diagnostic path.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
Bms Temp Low
Battery Under-Temperature (BMS)
The battery BMS reports an under-temperature condition.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for Bms Temp Low: Battery Under-Temperature (BMS)
Product fit
- H1(G2) Series · Single-phase hybrid inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
- AC1(G2) Series · AC-coupled inverter
  Confirmed · Manual V1.0.8 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Preserve the BMS alarm and temperature context and follow the battery supplier's diagnostic path before attempting charge or discharge outside the approved range.
Remedy sourceH1/AC1 G2 manual
Manufacturer / escalation handoff
1030
AC Overcurrent
The AC output current has exceeded the safe limit (R-series three-phase string inverter).
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1030: AC Overcurrent
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Allow the inverter to attempt its documented automatic recovery and record whether the alarm repeats. Contact your installer if it recurs.
Installer remedy
Confirm the AC output condition and follow the FoxESS service path for a recurring overcurrent; the manual does not prescribe an owner reset.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1034
DC Component Current Fault
A DC component has been detected in the output current beyond limits.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1034: DC Component Current Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Follow the model-specific controlled disconnection and reconnection sequence once. If the fault returns, preserve the alarm record and escalate to FoxESS rather than repeatedly resetting it.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1035
Leakage Overcurrent Fault
Excessive leakage (residual) current, often caused by high parasitic capacitance in poor light or moist conditions.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1035: Leakage Overcurrent Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and weather conditions. Do not reset the inverter, touch cables or operate isolators; arrange a licensed inspection if it persists or returns.
Installer remedy
Test the affected AC/DC insulation and earthing under the approved safe-isolation procedure. Locate damaged wiring, moisture ingress or an abnormal earth path before returning the system to service.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1040
Grid Voltage Imbalance
Imbalance between the grid phase voltages (three-phase R-series).
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1040: Grid Voltage Imbalance
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1042
Grid High Frequency
Grid frequency above the permitted limit (R-series 'Grid High Freq').
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1042: Grid High Frequency
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1043
Grid Low Frequency
Grid frequency below the permitted limit (R-series 'Grid Low Freq').
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1043: Grid Low Frequency
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1044
Grid Phase Voltage Over-Limit
A grid phase voltage has exceeded its limit (R-series 'Grid Phase Volt Over-limit').
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1044: Grid Phase Voltage Over-Limit
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1045
Grid Line Voltage Over-Limit
A grid line (phase-to-phase) voltage has exceeded its limit (R-series 'Grid Line Volt Over-limit').
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1045: Grid Line Voltage Over-Limit
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1051
Grid Phase Lost Fault
A grid phase has been lost on the three-phase supply.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1051: Grid Phase Lost Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record when the alarm occurs and whether the property has normal grid supply. The inverter should reconnect when the grid returns to range; contact your installer if it persists or repeats.
Installer remedy
Verify the grid supply and approved protection settings under the model procedure. Measure the relevant phases and escalate a confirmed supply abnormality through the authorised network process.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1066
DC Input MPPT1 Reverse Fault
The PV string on MPPT1 has reversed polarity.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1066: DC Input MPPT1 Reverse Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Do not touch PV cables or connectors. Record the code and contact the responsible installer before the system is operated again.
Installer remedy
Under approved safe isolation and the product procedure, verify the affected MPPT polarity and correct it only under the conditions specified by FoxESS.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1099
Over-Temperature Protection
The inverter has triggered over-temperature protection.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1099: Over-Temperature Protection
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
From a safe position, note direct sun and any visible obstruction at the air outlet. Do not touch the fan or open the inverter; contact your installer if it does not recover after cooling.
Installer remedy
Check installation shading, cooling airflow and fan alarms under the maintenance procedure. Clear the outlet safely or arrange service if the alarm persists.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1116
Ground Impedance Fault
Abnormal ground (earth) impedance detected.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1116: Ground Impedance Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Do not reset the inverter or touch electrical equipment. Record the code and arrange a licensed inspection.
Installer remedy
Check protective-earth connections and insulation between earth and live conductors under the approved safe-isolation procedure before returning the inverter to service.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1123
Grid Relay Fault
Fault in the grid relay.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1123: Grid Relay Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Follow the model-specific controlled disconnection and reconnection sequence once. If the fault returns, preserve the alarm record and escalate to FoxESS rather than repeatedly resetting it.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1124
Insulation Resistance Low Fault
PV array insulation (ISO) resistance to ground is too low.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1124: Insulation Resistance Low Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and weather conditions. Do not reset the inverter, touch cables or operate isolators; arrange a licensed inspection if it persists or returns.
Installer remedy
Verify the configured ISO protection value against local requirements, then inspect DC cable condition and earth contact under approved safe isolation. Recheck weather-related events only after conditions improve.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1145
Arc Fault
An arc fault has been detected on the DC side (AFCI protection).
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1145: Arc Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Treat this as a safety alarm. Do not clear it in the app, reset the inverter or touch PV wiring; keep clear and contact the responsible installer promptly.
Installer remedy
Disconnect the DC input under the authorised procedure and inspect the affected circuit for damaged cables, loose terminals or fuses, and burn marks. Clear the alarm only after the cause is rectified.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1188
AC SPD Abnormality
The AC surge protection device (SPD) is abnormal.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1188: AC SPD Abnormality
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Inspect the AC surge-protection device status under safe isolation and replace or service it through the authorised process before relying on the protection path.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1189
DC SPD Abnormality
The DC surge protection device (SPD) is abnormal.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1189: DC SPD Abnormality
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Inspect the DC surge-protection device status under safe isolation and replace or service it through the authorised process before relying on the protection path.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1191
External Fan Alarm
The external cooling fan has alarmed, e.g. blocked by debris.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1191: External Fan Alarm
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
From a safe position, look for a visible obstruction around the external fan. Do not touch the fan or open the inverter; contact your installer.
Installer remedy
Under the maintenance and safe-isolation procedure, remove external fan obstructions and verify fan operation. Escalate a continuing alarm to FoxESS.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1193
EEPROM Read-Write Alarm
Internal communication / EEPROM read-write abnormality.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1193: EEPROM Read-Write Alarm
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Follow the model-specific controlled disconnection and reconnection sequence once. If the fault returns, preserve the alarm record and escalate to FoxESS rather than repeatedly resetting it.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1313
DC Input MPPT1 Voltage High Fault
The DC input voltage on MPPT1 is too high.
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1313: DC Input MPPT1 Voltage High Fault
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Leave the inverter and PV wiring alone, record the code and contact your installer. Do not reset the inverter or operate isolators to test whether it clears.
Installer remedy
Measure the affected MPPT input under the approved procedure and compare it with the exact inverter limit and temperature-corrected string design before reconnection.
Remedy sourceR-Series manual
Manufacturer / escalation handoff
1345
String1 Warning
A warning for PV String 1 (e.g. unreliable connection or a damaged DC fuse).
Product fit · Confirmed · R75 / R100 / R110
Show field stepsHide field steps for 1345: String1 Warning
Product fit
- R75 / R100 / R110 · Three-phase string inverter
  Confirmed · Manual V1.4 · AU/region not confirmed · Firmware not documented
Safe checks now
Record the exact alarm, inverter model and time. Do not operate isolators, open equipment or change installer settings; contact your installer if the alarm remains.
Installer remedy
Verify the affected MPPT connection and DC fuse under approved safe isolation. Replace a damaged fuse with the specified part and escalate if the warning remains.
Remedy sourceR-Series manual
Manufacturer / escalation handoff

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Good to know

Frequently asked

Where do these FoxESS fault codes come from?: Compiled from publicly available FoxESS inverter and battery documentation and field references, then rewritten for the trade. Wattbench is independent and not affiliated with FoxESS.
Which of these can I clear on site?: Some clear on their own once grid or environmental conditions return to normal. Anything involving DC isolation, AC switching, wiring or opening the unit is licensed electrical work. Isolate safely, follow AS/NZS 5033 and AS/NZS 3000 procedure and use appropriate PPE before touching a live system.
The exact code isn't listed. Why not?: Firmware and model variants differ, and manufacturers revise their code tables. We document the most common ones; for a variant that isn't here, check the unit's current manual or the manufacturer's service portal.
How current is this reference?: This reference was last reviewed on 2 August 2026. We revise entries when the underlying manufacturer documentation changes.

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