Deye Inverter Fault Codes
Common Deye string and hybrid inverter fault codes decoded, with plain-English causes and fixes.
- Manufacturer
- Deye (SUN-series string & hybrid inverters)
- Codes documented
- 23
- Source
- Manufacturer documentation
- Scope
- Reference only
Deye builds the SUN-series string and hybrid inverters sold across Australia, and the same hardware and fault-code family is widely rebadged under other brands (Sunsynk being the best-known example), so this list applies broadly. Faults appear on the screen or app as an "F" code (F01-F64). Most are self-clearing grid or operating-mode events; a smaller group point to a genuine wiring, PV, battery or hardware problem. Important: the F-number for a given fault is NOT stable across firmware versions and regional model variants of the same SG04LP3 hardware. Direct decoding of Deye's own current manuals shows this clearly: the official Australian (2022) and global EU (2026) manuals BOTH number the ground-fault/start self-check as F07 (DC_START_FAILURE), use F46 for a battery fault, and contain NO F08 and NO F35 at all - whereas the firmware actually running on many deployed units (and the Sunsynk rebadge of the same board) reports the GFDI relay check as F08 and "no grid" as F35. This list documents the codes as owners and installers most commonly see them in the field, but every number must be confirmed against the exact manual and firmware for your specific unit before acting. Safety note: A Deye inverter has live PV DC, battery DC and grid AC inside it even when the screen is dark. Doing the basics - reading the code, checking it isn't a momentary grid event, and a clean restart - is fine for an owner, but anything involving the DC isolator, AC wiring, opening the unit, or working on PV/battery cabling is licensed-electrician (and CEC-accredited installer) territory in Australia. If a code keeps returning after a restart, log it and call your installer rather than persisting.
- 23 Deye (SUN-series string & hybrid inverters) fault and alarm codes, documented in plain English.
- Compiled from manufacturer documentation — independent and not affiliated with Deye (SUN-series string & hybrid inverters).
- Codes involving DC/AC isolators, wiring or opening the unit are licensed-electrician work — when in doubt, call your installer.
23 of 23 codes
- F08
GFDI relay failure
The inverter's ground-fault detection (GFDI) relay has failed a self-test, or the neutral/earth bonding doesn't match the configured grid type. On deployed firmware and rebadged (Sunsynk) units this is one of the most-reported codes and is very often a grid-type setting mismatch (e.g. set to 120/240V split-phase when the system is actually single-phase) rather than a true hardware fault. (Note: the current official Deye AU and EU manuals do NOT list an F08 - they number the equivalent start/ground self-check as F07. Confirm against your unit's firmware.)
What to do
First confirm the configured Grid Type matches the actual supply (single phase vs split/three phase) - on single-phase units, setting Grid Type to Single Phase commonly clears it. Power-cycle the inverter cleanly (ideally restart from battery with AC and PV DC isolated). If it persists, the neutral-to-earth bonding at the backup/load port and the GFDI relay itself need checking - that is electrical work for your CEC-accredited installer or a licensed electrician; do not open the unit or alter earthing yourself.
- F13
Working mode / grid mode changed
An informational event, not a hardware fault. The official manual logs it when the grid type or frequency setting changes, when the battery mode is switched to 'No battery', or (on some older firmware) when the system work mode changes. It normally clears itself.
What to do
Usually no action needed - it clears automatically. If it stays, turn off the DC isolator and AC switch, wait about one minute, then turn the AC and DC back on. If it still won't clear, contact your installer.
- F15
AC over-current (software)
The inverter's software protection has detected excessive current on the AC side (listed in the official manual as 'AC over current fault of software'). Can be triggered by a heavy backup or common load, or by an AC sensing issue.
What to do
Check that backup-load and household-load demand are within the inverter's rated range and reduce load if needed, then restart. If it persists it points to an internal sensor or loose AC connection - that is for your installer or a licensed electrician, not an owner.
- F16
AC leakage current fault
The residual-current monitor has detected earth-leakage current above its threshold (official manual: 'AC leakage current fault'), which can indicate a PV array insulation problem or moisture in connectors. The manual's listed remedy focuses on the PV-side cable ground connection.
What to do
Restart the inverter; transient leakage (e.g. damp panels in the morning) often clears on its own - the manual suggests restarting two or three times. If it keeps returning, the PV array, cabling and earthing need inspection by your CEC-accredited installer - leakage faults can indicate a genuine insulation hazard, so don't ignore a persistent one.
- F18
AC over-current (hardware)
A hardware-level over-current trip on the AC side (official manual: 'AC over current fault of hardware'), typically from too much load on the backup and/or common-load outputs.
What to do
Check that backup-load power and common-load power are within the allowed range, reduce load, and restart to see if it clears. If it persists, contact your installer.
- F20
DC over-current (hardware)
A hardware-level over-current trip on the DC side (PV or battery) - official manual: 'DC over current fault of the hardware'. Common when an off-grid/backup system is started into a large load, where inrush current briefly exceeds limits.
What to do
Check the PV and battery connections. If it appeared on off-grid startup with a big load, reduce the connected load. Turn off the DC isolator and AC switch, wait one minute, then turn them back on. If it persists, contact your installer; DC isolator and cabling work is licensed-electrician work.
- F22
Emergency stop / remote shutdown (Tz_EmergStop_Fault)
The inverter has been shut down by a remote-control or emergency-stop signal - it is being commanded off, not failing. The official manual states 'it tells the inverter is remotely controlled'.
What to do
This indicates remote control is active. Contact your installer to confirm why the remote-shutdown signal is present before trying to override it.
- F23
Transient leakage / GFCI over-current (Tz_GFCI_OC_Fault)
A transient earth-leakage (residual-current) over-current event, often linked to PV-side earthing. Confirmed in the official manual as 'Tz_GFCI_OC current is transient over current / leakage current fault'.
What to do
Check the PV-side cable ground connection. Restart the system two or three times to see if the transient clears. If the fault remains, have your installer inspect PV earthing and insulation - persistent leakage is a safety item.
- F24
DC insulation / isolation impedance failure
PV insulation resistance to earth is too low - the array's isolation impedance has dropped (official manual: 'DC insulation failure - PV isolation resistance is too low'), which can mean a damaged cable, water ingress, or a faulty panel/connector.
What to do
Check that PV panel-to-inverter connections are firm and correct and that the inverter's PE (earth) cable is properly connected to ground. This is an insulation safety fault: have your CEC-accredited installer test the array. Do not handle DC cabling or open the unit yourself.
- F26
DC busbar unbalanced
The internal DC busbar is unbalanced. The official manual notes it is logged when load across the phases is very uneven, and that it can also indicate DC leakage current.
What to do
Wait a short while and check whether it normalises. Where possible, balance the loads across phases (or across L1/L2 on split-phase). Restart the system two or three times if it persists, then contact your installer.
- F29
Parallel CAN bus fault
A communication fault on the parallel-link (CAN) bus between inverters in a multi-unit/parallel system. The official manual notes it is normal to see this briefly while a parallel system is powering up, and it clears once all units are ON.
What to do
On startup, ignore it if it self-clears once all inverters are running. If it stays, check the parallel communication cable connections and that each inverter's communication address is set correctly. Contact your installer if it persists.
- F34
AC overload fault
The connected load exceeds what the inverter can supply (official manual: 'AC Overcurrent fault'), typically on the backup/EPS output. A common owner-facing code when too many appliances run at once on backup power.
What to do
Reduce the load so it sits within the inverter's rated output, then let it recover or restart. Check what was running when it tripped - large motors/heaters are usual culprits. If it trips with modest load, contact your installer.
- F35
No AC grid (AC_NoUtility_Fault)
The inverter cannot detect a valid utility grid - i.e. the grid is absent or out of acceptable voltage/frequency range. Often simply a grid outage or a tripped supply breaker; on three-phase units it can also be caused by incorrect phase rotation/sequence. (Note: this F35 numbering is from deployed/Sunsynk firmware; the current official Deye manuals do not list an F35 - confirm against your unit.)
What to do
Confirm whether grid power is actually present and that the AC supply breaker/isolator hasn't tripped. For a genuine outage, a hybrid system should switch to backup automatically and the code clears when the grid returns. If grid is present but the inverter still reports no utility, the AC connection (and on three-phase, the phase sequence) needs checking by a licensed electrician.
- F41
Parallel system stop
In a parallel installation, one inverter has shut down, which causes the other paralleled inverters to report F41 and stop as a group (official manual: 'if there is 1 pcs hybrid inverter shutdown, all hybrid inverters will report F41').
What to do
Check the working status of each hybrid inverter in the parallel group to find which unit went down. Resolve that unit's underlying fault. If the cause isn't clear, contact your installer.
- F42
AC line low voltage
Measured grid (AC line) voltage is below the allowed range (official manual: 'AC line low voltage / grid voltage fault'). Frequently a grid-side condition (sagging supply) rather than an inverter fault.
What to do
Check whether the AC voltage is within the standard range and that the grid AC cables are firmly and correctly connected. Persistent under-voltage with a healthy grid, or any cabling check, is for a licensed electrician / your installer.
- F46
Backup battery fault
A fault with the connected battery (or batteries). The official Deye AU and EU manuals decode F46 as 'backup battery fault' and advise checking each battery's status - voltage, SOC and parameter settings - and making sure all parameters match. (Earlier third-party lists mislabelled F46 as 'AC under-voltage'; the decoded official manuals do not support that - treat F46 as a battery fault.)
What to do
Check each battery's status - voltage, state of charge and configured parameters - and make sure all units are set up consistently. If the fault persists, contact your installer to inspect the battery and its settings; battery DC work is licensed-electrician territory.
- F47
AC over-frequency
Grid frequency is above the allowed range, so the inverter disconnects per grid-protection (anti-islanding) rules. Usually a grid-side event.
What to do
Check whether the frequency is within specification and that AC cables are firmly connected. This is normally a transient grid condition that clears itself; if it recurs constantly, contact your installer.
- F48
AC under-frequency
Grid frequency is below the allowed range, so the inverter disconnects per grid-protection rules (official manual: 'AC lower frequency - grid frequency out of range'). Usually a grid-side event.
What to do
Check whether the frequency is within specification and that AC cables are firmly connected. Generally a transient grid condition that self-clears; if it persists, contact your installer.
- F55
DC bus voltage too high
The internal DC bus (busbar) voltage is too high (official manual: 'DC busbar voltage is too high - BUS voltage is too high') - typically because battery voltage or PV input voltage is above the allowed range.
What to do
Check whether the battery voltage is too high and confirm the PV input voltage is within the inverter's allowed range (over-sized/cold strings can push voltage up). If string voltage is the cause, your installer needs to review the array design. DC cabling work is licensed-electrician work.
- F56
DC bus voltage too low
The internal DC bus (busbar) voltage is too low - most often a flat or very low battery, or insufficient PV. Confirmed in the official manual as 'DC busbar voltage is too low - battery voltage low'.
What to do
Check whether the battery voltage is too low; if so, allow PV or the grid to charge the battery back up. If voltage stays low with a healthy battery, contact your installer.
- F58
BMS communication fault
Communication between the hybrid inverter and the battery BMS has been lost. The official manual flags it as a fault when the 'BMS_Err-Stop' protection is enabled and the BMS link drops (e.g. wrong comms cable, wrong battery protocol, or a loose RJ45).
What to do
Check the comms cable and connector between inverter and battery, and that the correct battery brand/protocol is selected. The 'BMS_Err-Stop' item can be disabled on the LCD if you don't want a comms drop to stop the inverter, but the underlying cause should still be fixed. Contact your installer if it persists.
- F63
ARC fault (AFCI)
The arc-fault detection (AFCI) circuit has detected a possible DC arc on the PV side. The official manual notes this detection is enabled for the US market; many AU units will not raise it.
What to do
Check the PV module cable connections, then clear the arc fault from the menu. Because an arc indicates a potentially dangerous loose/damaged DC connection, have your CEC-accredited installer inspect the PV wiring before returning the system to service. Do not handle DC cabling yourself.
- F64
Heat-sink high temperature failure
The inverter's heat sink is too hot and it has shut down to protect itself (official manual: 'Heatsink high temperature failure - heatsink temperature is too high') - usually caused by a hot/poorly ventilated install location or blocked airflow.
What to do
Check whether the surrounding temperature is too high and that airflow around the unit isn't blocked (clear vents, provide shade/ventilation). Turn the inverter off for about 10 minutes to cool, then restart. If it keeps overheating in normal conditions, contact your installer.
Sources
- Deye SUN-(5-12)K-SG04LP3-AU Hybrid Inverter User Manual - Fault information table (Chart 7-1), official deyeinverter.com (decoded directly)
- Deye SUN-5-12K-SG04LP3-EU Hybrid Inverter User Manual (2026 edition), official deyeinverter.com (decoded directly)
- Deye SUN-8-12K-SG04LP3 Hybrid Inverter User Manual ver2.0 (official deyeinverter.com)
- Deye Fault Codes 5KW-8KW - descriptions and solutions (Solar Deals, mirrors deployed Deye fault list)
- Sunsynk inverter fault code list (Sunsynk support, same-OEM hardware)
- F08 - GFDI Relay Failure error message (Sunsynk support: single-phase vs split-phase grid-type fix)
- Deye 8K grounding fault - Error F08 GFDI_Relay_Failure (DIY Solar Power Forum, real Deye-branded unit)
- F35 AC_NoUtility_Fault error - Deye SG04LP3 field discussion (DIY Solar Power Forum)
Frequently asked
- Where do these Deye fault codes come from?
- We compile them from publicly available Deye inverter documentation and field references, then rewrite each entry in plain English. Solar Analytica is independent and not affiliated with Deye.
- Can I clear these faults myself?
- Some clear automatically once conditions return to normal. Anything involving DC isolators, AC switches, wiring or opening the unit is licensed-electrician work — if in doubt, contact your installer rather than working on a live system.
- My exact code isn't listed — why not?
- Firmware and model variants differ, and manufacturers occasionally revise their codes. We document the most common ones; if yours isn't here, check your inverter's manual or ask your installer.
- How current is this reference?
- Last reviewed June 2026. We revise it when the underlying manufacturer documentation changes.
Other inverter fault libraries
Inverter Fault Library
Huawei Inverter Error Codes
Major and minor alarm codes for Huawei SUN2000 residential and commercial inverters, with plain-English causes and field-tested fixes.
Inverter Fault Library
Sungrow Alarm Codes
The complete Sungrow fault reference — string, SH hybrid and battery families — with every alarm number searchable and grouped by root cause.
Inverter Fault Library
Solis Alarm Codes
Solis (Ginlong) inverter alarm codes covering grid, insulation, temperature and hardware faults, with diagnostic next steps.