SUN-5-12K-SG01HP3-EU-DM2 three-phase hybrid (F-series table)
Deye F31 error code
AC slave contactor or relay fault.
Likely causes
- Grid L/N orientation reversed
- Slave relay stuck or coil failure
- Relay driver circuit fault
Checks to run, in order
- 1Check the grid L/N orientation
- 2Check the relay operation
- 3Restart the inverter
Fixes
- Correct the L/N orientation
- Restart and restore factory settings
When to escalate
If the wiring is correct and F31 persists, the distributor should replace the contactor or control board.
Fix it with the right tools
Check the system around the fault before replacing parts: load, battery bank, PV string and commissioning settings. If you need a second opinion, send the code and your inverter model to our team.
Before you open the inverter
- Isolate both the AC and DC sides, then confirm the display is dead before touching terminals.
- Use insulated tools and one hand where possible. DC arcs do not self-extinguish like AC.
- If you see burnt terminals, swollen cells, leaking electrolyte or a burning smell, stop and escalate instead of resetting the fault.
Questions installers ask
What does Deye F31 mean?
AC slave contactor or relay fault.
How do I fix Deye F31?
Correct the L/N orientation Restart and restore factory settings
When should I escalate Deye F31?
If the wiring is correct and F31 persists, the distributor should replace the contactor or control board.
Can I reset Deye F31 myself?
Only after isolating the AC and DC sides and running the checks above. If Deye F31 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Deye F31?
Deye F31 is documented for SUN-5-12K-SG01HP3-EU-DM2 three-phase hybrid (F-series table). Confirm the code on your own unit's display or manual before ordering parts.
More Deye error codes
- Deye F01PV input polarity is reversed at one or both DC inputs.
- Deye F02PV insulation resistance to earth is below the safety limit.
- Deye F03Ground fault detected on the PV array (GFDI).
- Deye F04GFDI ground-failure alarm: the PV array or inverter is not properly earthed.
- Deye F05Control-board EEPROM read failure.
- Deye F06Control-board EEPROM write failure.
Guidance reviewed 17 October 2026 by the Mishka Energy installer team. Error codes vary by brand, model family and firmware; confirm against the manufacturer manual.
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