Where do these Hoymiles fault codes come from?

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

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 3 August 2026. We revise entries when the underlying manufacturer documentation changes.

Microinverter Fault Library

Hoymiles Microinverter Error Codes

Current official HMS/HMT alarms and remedies, separated from community-only OpenDTU decoder entries that remain remedy-blank.

Sources listedReviewed August 2026Source: Official current HMS/HMT manuals and separately labelled community decoder referencesOur methodology

Manufacturer: Hoymiles (HM / MI / HMS / HMT-series microinverters and the DTU monitoring gateway)
Codes documented: 30
Source: Official current HMS/HMT manuals and separately labelled community decoder references
Scope: Current global HMS/HMT remedies; Australian variant and firmware not confirmed

30 of 30 codes

About this fault librarySources · scope

Hoymiles alarm codes vary by microinverter family and firmware. Codes 121 and 124–149 now resolve to official current HMS/HMT troubleshooting tables; code 124 was upgraded from community-only after recovery in the current HMS manual. Codes 11–73 and 9000 remain search aids from the community-maintained OpenDTU decoder because no matching official instruction was found; they stay explicitly remedy-blank. The cited manuals are global family references and do not establish the installed Australian variant or firmware. Confirm the exact model in S-Miles before acting. Safety note: owners should record the code and app status. AC/DC disconnection, measurements, wiring, connectors and protection settings are qualified-installer tasks.

Key takeaways

30 Hoymiles (HM / MI / HMS / HMT-series microinverters and the DTU monitoring gateway) fault and alarm codes, documented for the trade.
Compiled from published documentation and field references; Wattbench is independent and not affiliated with Hoymiles (HM / MI / HMS / HMT-series microinverters and the DTU monitoring gateway).
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.

11
Grid voltage surge
Community decoder: a sudden grid-voltage surge was reported. This label was not found in the reviewed manufacturer manuals.
12
Grid voltage sharp drop
Community decoder: a sudden grid-voltage drop was reported. This label was not found in the reviewed manufacturer manuals.
13
Grid frequency mutation
Community decoder: an abrupt grid-frequency change was reported. This label was not found in the reviewed manufacturer manuals.
14
Grid phase mutation
Community decoder: an abrupt grid-phase change was reported. This label was not found in the reviewed manufacturer manuals.
36
INV overvoltage or overcurrent
Community decoder: protection operated in the inverter stage. This label was not found in the reviewed manufacturer manuals.
46
FB overvoltage
Community decoder: overvoltage in the flyback stage. This label was not found in the reviewed manufacturer manuals.
47
FB overcurrent
Community decoder: overcurrent in the flyback stage. This label was not found in the reviewed manufacturer manuals.
48
FB clamp overvoltage
Community decoder: flyback-clamp overvoltage. This label was not found in the reviewed manufacturer manuals.
49
FB clamp overvoltage
Community decoder: a second flyback-clamp overvoltage event. This label was not found in the reviewed manufacturer manuals.
71
Grid overvoltage load reduction (VW) enabled
Community decoder: Volt–Watt load reduction is active. This label was not found in the reviewed manufacturer manuals.
72
Grid overfrequency load reduction (FW) enabled
Community decoder: Frequency–Watt load reduction is active. This label was not found in the reviewed manufacturer manuals.
73
Over-temperature load reduction (TW) enabled
Community decoder: temperature-based load reduction is active. This label was not found in the reviewed manufacturer manuals.
121
Over temperature protection
The microinverter has shut down on over-temperature protection because internal/ambient temperature exceeded safe limits.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 121: Over temperature protection
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
From a safe position, keep the array area unobstructed and record unusual heat or poor airflow. Do not go onto the roof; contact the installer if the alarm remains in normal conditions.
Installer remedy
Check the microinverter installation ventilation and ambient conditions against the exact HMS/HMT manual. Improve heat dissipation where required and escalate if suitable conditions do not clear the alarm.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
124
Shut down by remote control
Current HMS family: the microinverter reports a remote shutdown command. The official handling path checks zero-export management and whether the unit was manually shut down.
Product fit · Confirmed · HMS-300/350/400/450/500-1T
Show field stepsHide field steps for 124: Shut down by remote control
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record that remote shutdown is reported and check only the visible S-Miles status. Do not override zero-export controls or operate equipment; contact the installer if the command is unexpected.
Installer remedy
Check zero-export management and the manual shutdown state using the HMS manual. Correct the command source rather than treating code 124 as an internal hardware fault, then escalate if it persists.
Remedy sourceHMS 1T manual
Manufacturer / escalation handoff
125
Grid configuration parameter error
The grid profile / grid configuration parameters loaded on the microinverter are incorrect or invalid.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 125: Grid configuration parameter error
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the code and app status. Do not change the grid profile, firmware or device assignment; contact the installer if the alarm is frequent or does not recover.
Installer remedy
Verify the exact model's grid configuration or firmware and the DTU communication path using the HMS/HMT manual. Use only Hoymiles-supplied files and escalate a recurring software event.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
126
Software error code 126
Internal software/firmware error reported by the microinverter. Often transient.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 126: Software error code 126
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the code and app status. Do not change the grid profile, firmware or device assignment; contact the installer if the alarm is frequent or does not recover.
Installer remedy
Verify the exact model's grid configuration or firmware and the DTU communication path using the HMS/HMT manual. Use only Hoymiles-supplied files and escalate a recurring software event.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
127
Firmware error
A firmware error was detected on the microinverter, typically related to a firmware version or failed upgrade.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 127: Firmware error
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the code and app status. Do not change the grid profile, firmware or device assignment; contact the installer if the alarm is frequent or does not recover.
Installer remedy
Verify the exact model's grid configuration or firmware and the DTU communication path using the HMS/HMT manual. Use only Hoymiles-supplied files and escalate a recurring software event.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
128
Software error code 128
Internal software/firmware error reported by the microinverter. Often transient.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 128: Software error code 128
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the code and app status. Do not change the grid profile, firmware or device assignment; contact the installer if the alarm is frequent or does not recover.
Installer remedy
Verify the exact model's grid configuration or firmware and the DTU communication path using the HMS/HMT manual. Use only Hoymiles-supplied files and escalate a recurring software event.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
129
Software error code 129
The manufacturer troubleshooting table identifies an internal software error.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 129: Software error code 129
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the code and app status. Do not change the grid profile, firmware or device assignment; contact the installer if the alarm is frequent or does not recover.
Installer remedy
Verify the exact model's grid configuration or firmware and the DTU communication path using the HMS/HMT manual. Use only Hoymiles-supplied files and escalate a recurring software event.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
130
Offline
The microinverter is offline. The DTU cannot communicate with it / it is not reporting to the monitoring system.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 130: Offline
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Check the microinverter's last-report time in S-Miles and record which unit is offline. Do not operate solar switches or go onto the roof; contact the installer if it remains offline.
Installer remedy
Confirm the recorded serial number and separate DTU-to-cloud from DTU-to-microinverter communication using the exact HMS/HMT procedure. Correct the communication path before considering device replacement.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
141
Grid overvoltage
AC grid voltage exceeded the upper protection limit, so the microinverter stopped feeding in.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 141: Grid overvoltage
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and whether the premises supply appears normal. It may recover when the grid returns to range; do not change grid limits and contact the installer if it repeats.
Installer remedy
Check the measured grid voltage, frequency or rate of change against the exact HMS/HMT profile. Obtain the local network operator's consent before any protection-limit change and escalate persistent supply abnormalities.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
142
10 min value grid overvoltage
The 10-minute average grid voltage exceeded the allowed limit (sustained overvoltage protection).
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 142: 10 min value grid overvoltage
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and whether the premises supply appears normal. It may recover when the grid returns to range; do not change grid limits and contact the installer if it repeats.
Installer remedy
Check the measured grid voltage, frequency or rate of change against the exact HMS/HMT profile. Obtain the local network operator's consent before any protection-limit change and escalate persistent supply abnormalities.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
143
Grid undervoltage
AC grid voltage fell below the lower protection limit.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 143: Grid undervoltage
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and whether the premises supply appears normal. It may recover when the grid returns to range; do not change grid limits and contact the installer if it repeats.
Installer remedy
Check the measured grid voltage, frequency or rate of change against the exact HMS/HMT profile. Obtain the local network operator's consent before any protection-limit change and escalate persistent supply abnormalities.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
144
Grid overfrequency
AC grid frequency exceeded the upper protection limit.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 144: Grid overfrequency
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and whether the premises supply appears normal. It may recover when the grid returns to range; do not change grid limits and contact the installer if it repeats.
Installer remedy
Check the measured grid voltage, frequency or rate of change against the exact HMS/HMT profile. Obtain the local network operator's consent before any protection-limit change and escalate persistent supply abnormalities.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
145
Grid underfrequency
AC grid frequency fell below the lower protection limit.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 145: Grid underfrequency
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and whether the premises supply appears normal. It may recover when the grid returns to range; do not change grid limits and contact the installer if it repeats.
Installer remedy
Check the measured grid voltage, frequency or rate of change against the exact HMS/HMT profile. Obtain the local network operator's consent before any protection-limit change and escalate persistent supply abnormalities.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
146
Rapid grid frequency change rate
The rate of change of grid frequency (ROCOF) exceeded the allowed limit.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 146: Rapid grid frequency change rate
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Record the alarm, time and whether the premises supply appears normal. It may recover when the grid returns to range; do not change grid limits and contact the installer if it repeats.
Installer remedy
Check the measured grid voltage, frequency or rate of change against the exact HMS/HMT profile. Obtain the local network operator's consent before any protection-limit change and escalate persistent supply abnormalities.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
147
Power grid outage
The microinverter detected a grid outage.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 147: Power grid outage
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Confirm whether the premises has grid supply and record the alarm. Do not operate solar switches or rooftop equipment; contact the installer if normal supply is present but the alarm remains.
Installer remedy
Check the AC supply, connection and anti-islanding condition under the exact HMS/HMT procedure. Restore service only after a stable grid and sound AC connection are confirmed.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
148
Grid disconnection
The microinverter detected disconnection from the grid (loss of AC connection).
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 148: Grid disconnection
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Confirm whether the premises has grid supply and record the alarm. Do not operate solar switches or rooftop equipment; contact the installer if normal supply is present but the alarm remains.
Installer remedy
Check the AC supply, connection and anti-islanding condition under the exact HMS/HMT procedure. Restore service only after a stable grid and sound AC connection are confirmed.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
149
Island detected
Anti-islanding protection tripped. The microinverter detected an islanding condition and disconnected for safety.
Product fit · Confirmed · 2 documented families
Show field stepsHide field steps for 149: Island detected
Product fit
- HMS-300/350/400/450/500-1T · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
- HMT-1600/1800/2000-4T LA · Role not confirmed
  Confirmed · AU/region not confirmed · Firmware not documented
Safe checks now
Confirm whether the premises has grid supply and record the alarm. Do not operate solar switches or rooftop equipment; contact the installer if normal supply is present but the alarm remains.
Installer remedy
Check the AC supply, connection and anti-islanding condition under the exact HMS/HMT procedure. Restore service only after a stable grid and sound AC connection are confirmed.
Remedy sourceHMS 1T manual HMT manual
Manufacturer / escalation handoff
9000
Microinverter suspected stolen
Community decoder: an anti-theft event was reported. This code was not found in the reviewed manufacturer manuals.

Sources

ManufacturerHoymiles HMS-300/350/400/450/500-1T single-phase microinverter user manual
ManufacturerHoymiles HMT-1600/1800/2000-4T LA user manual
ManufacturerHoymiles HM-600/700/800 global user manual
ManufacturerHoymiles HM-1200NT/1500NT North America user manual
CommunityOpenDTU: unknown Hoymiles alarm codes
CommunityOpenDTU: Hoymiles AlarmLogParser discussion
CommunityOpenDTU: alarm-code compilation discussion

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Good to know

Frequently asked

Where do these Hoymiles fault codes come from?: Compiled from publicly available Hoymiles inverter and battery documentation and field references, then rewritten for the trade. Wattbench is independent and not affiliated with Hoymiles.
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 3 August 2026. We revise entries when the underlying manufacturer documentation changes.

Keep exploring

Other fault libraries

Inverter Fault Library

Grid voltage surge

Grid voltage sharp drop

Grid frequency mutation

Grid phase mutation

INV overvoltage or overcurrent

FB overvoltage

FB overcurrent

FB clamp overvoltage

FB clamp overvoltage

Grid overvoltage load reduction (VW) enabled

Grid overfrequency load reduction (FW) enabled

Over-temperature load reduction (TW) enabled

Over temperature protection

Product fit

Safe checks now

Installer remedy

Shut down by remote control

Product fit

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Installer remedy

Grid configuration parameter error

Product fit

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Installer remedy

Software error code 126

Product fit

Safe checks now

Installer remedy

Firmware error

Product fit

Safe checks now

Installer remedy

Software error code 128

Product fit

Safe checks now

Installer remedy

Software error code 129

Product fit

Safe checks now

Installer remedy

Offline

Product fit

Safe checks now

Installer remedy

Grid overvoltage

Product fit

Safe checks now

Installer remedy

10 min value grid overvoltage

Product fit

Safe checks now

Installer remedy

Grid undervoltage

Product fit

Safe checks now

Installer remedy

Grid overfrequency

Product fit

Safe checks now

Installer remedy

Grid underfrequency

Product fit

Safe checks now

Installer remedy

Rapid grid frequency change rate

Product fit

Safe checks now

Installer remedy

Power grid outage

Product fit

Safe checks now

Installer remedy

Grid disconnection

Product fit

Safe checks now

Installer remedy

Island detected

Product fit

Safe checks now

Installer remedy