SUN-5-12K-SG01HP3-EU-DM2 three-phase hybrid (F-series table)
Deye F12 error code
AC slave contactor failed to close or report correctly.
Likely causes
- Slave contactor coil or driver failure
- Stuck or pitted slave contactor contacts
- Loose control wiring
- Control-board fault
Checks to run, in order
- 1Listen for the slave contactor closing
- 2Measure AC at the backup output
- 3Inspect the contactor control wiring
- 4Restart and read the fault history
Fixes
- Restart and restore factory settings
- Correct any loose AC or control wiring
When to escalate
If the slave contactor still does not operate, the contactor or control board must be replaced by the distributor.
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 F12 mean?
AC slave contactor failed to close or report correctly.
How do I fix Deye F12?
Restart and restore factory settings Correct any loose AC or control wiring
When should I escalate Deye F12?
If the slave contactor still does not operate, the contactor or control board must be replaced by the distributor.
Can I reset Deye F12 myself?
Only after isolating the AC and DC sides and running the checks above. If Deye F12 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Deye F12?
Deye F12 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.
Back to troubleshooting