31Fault

DEYE inverter error 31 (F031)

Relay open circuit fault

Also displayed as F031 / F31 on some models.

Fault — the inverter cuts its output and the red LED stays solid until the fault is cleared.

The exact meaning depends on your model:

SUN G01P3-EU-BM8 Series

InverterFault

Also applies to:SUN-120K-G01P3-EU-BM8SUN-125K-G01P3-EU-BM8SUN-130K-G01P3-EU-BM8SUN-135K-G01P3-EU-BM8SUN-136K-G01P3-EU-BM8

What it means

Relay open circuit fault — At least one AC relay cannot close.

Cause: At least one relay cannot be closed - a relay fault or a faulty relay driver signal (old inverters have no relay detection function).

How to fix it

  1. Check the relays and their driver signals
  2. Restart the inverter; if the fault still exists, contact your installer or Deye service.

Source: sun-120k-g01p3-eu-bm8-sun-125k-g01p3-eu-bm8-sun-130k-g01p3-eu-bm8-manual.pdf, p.62

SUN G02P1-EU Series

InverterFault

Also applies to:SUN-7K-G02P1-EU-AM2SUN-7.5K-G02P1-EU-AM2SUN-8K-G02P1-EU-AM2SUN-9K-G02P1-EU-AM2SUN-10K-G02P1-EU-AM2SUN-10.5K-G02P1-EU-AM2

What it means

Dc boost soft start — DC boost soft-start fault. Marked 'Not available' in the manual for these models.

Cause: Fault of the DC boost soft-start stage; this code is not used on these single-phase models.

How to fix it

  1. Marked 'Not available' in the manual - this code is not used on these models.
  2. If it is displayed nonetheless, restart the inverter and contact your installer or Deye service.

Source: sun-7k-g02p1-eu-am2-sun-7-5k-g02p1-eu-am2-sun-8k-g02p1-eu-am2-manual.pdf, p.52 · sun-9k-g02p1-eu-am2-sun-10k-g02p1-eu-am2-sun-10-5k-g02p1-eu-am2-manual.pdf, p.52

SUN G03/G01P3-AM8 Series

InverterFault

Also applies to:SUN-60K-G03SUN-70K-G03SUN-75K-G03SUN-80K-G03SUN-90K-G03SUN-100K-G03SUN-110K-G03SUN-60K-G01P3-EU-AM8-LV+7

What it means

Relay open circuit fault — At least one AC relay cannot close.

Cause: At least one relay cannot be closed - a relay fault or a faulty relay driver signal (old inverters have no relay detection function).

How to fix it

  1. Check the relays and their driver signals
  2. Restart the inverter; if the fault still exists, contact your installer.

Source: sun-70k-g03-sun-75k-g03-sun-80k-g03-sun-90k-g03-sun-100k-g03-sun-110k-g03-manual.pdf, p.62 · sun-120k-g01p3-eu-am8-manual.pdf, p.61 · sun-60k-g01p3-eu-am8-lv-sun-70k-g01p3-eu-am8-lv-sun-75k-g01p3-eu-am8-lv-manual.pdf, p.61 · +1 more official manuals

SUN G04/G05/G06 3-Phase

InverterFault

Also applies to:SUN-6K-G06-LV-P1SUN-8K-G06-LV-P1SUN-6K-G06P3-EU-BM2-LV-P1SUN-8K-G06P3-EU-BM2-LV-P1SUN-10K-G05-LVSUN-12K-G05-LVSUN-15K-G05-LVSUN-15K-G06P3-EU-BM2-P1+48

What it means

Relay open circuit fault — At least one grid relay cannot close (open circuit detected).

Cause: A relay or its driver signal is faulty, so at least one relay cannot be closed (old inverters have no relay detection function).

How to fix it

  1. Check the relays and their driver signals.
  2. Restart the inverter; if the fault still exists, contact your installer or Deye service.

Source: sun-6k-g06-lv-p1-manual.pdf, p.58 · sun-7k-g06p3-eu-bm2-sun-8k-g06p3-eu-bm2-sun-9k-g06p3-eubm2-sun-10k-g06p3-eu-bm2-sun-12k-g06p3-eu-bm2-manual.pdf, p.57

SUN G04P1/G05P1 Series

InverterFault

Also applies to:SUN-1K-G04P1-EU-AM1SUN-1.5K-G04P1-EU-AM1SUN-2K-G04P1-EU-AM1SUN-2.2K-G04P1-EU-AM1SUN-2.5K-G04P1-EU-AM1SUN-2.7K-G04P1-EU-AM1SUN-3K-G04P1-EU-AM1SUN-3.3K-G04P1-EU-AM1+15

What it means

Dc boost soft start — DC boost converter soft-start fault (marked 'Not available' on these models).

Cause: The DC boost stage failed its soft-start; this code is not used on these single-phase models.

How to fix it

Marked 'Not available' on these single-phase models - the code is not used.

Source: sun-2-7k-g04p1-eu-am1-sun-3k-g04p1-eu-am1-sun-3-3k-g04p1-eu-am1-sun-3-6k-g04p1-eu-am1-sun-4k-g04p1-eu-am1-manual.pdf, p.54

SUN SG01HP3/SG02HP3 Hybrid

InverterFault

Also applies to:SUN-5K-SG01HP3-EU-AM2SUN-6K-SG01HP3-EU-AM2SUN-8K-SG01HP3-EU-AM2SUN-10K-SG01HP3-EU-AM2SUN-12K-SG01HP3-EU-AM2SUN-15K-SG01HP3-EU-AM2SUN-20K-SG01HP3-EU-AM2SUN-25K-SG01HP3-EU-AM2+9

What it means

AC Slave Contactor Fault — AC_SlaveContactor_Fault - the slave AC contactor reported a fault.

Cause: The slave AC contactor failed its check; an incorrect grid orientation (wiring) can cause it.

How to fix it

  1. Check whether the grid orientation is correct
  2. Restart the inverter 3 times and restore the factory settings.

Source: sun-12k-sg01hp3-eu-am2-manual.pdf, p.50 · sun-29.9-30-35-40-50k-sg01hp3-eu-bm3-4-20260224-en-manual.pdf, p.51 · sun-60-70-75-80k-sg02hp3-eu-em6-20260224-en-manual.pdf, p.51

RW Spring Series Battery

BatteryFault

Also applies to:RW-L2.5ARW-L5.1RW-L10.2RW-F16SE-F5SE-F5 PlusSE-F5 ProSE-F12+7

What it means

PCS communication fails — The communication link between the battery and the inverter/PCS dropped.

Cause: The CAN link (500 kbps) between the battery COM port and the inverter's BMS port failed - loose or miswired cable, wrong pin order, or the wrong battery-protocol selection on the inverter.

How to fix it

  1. Check the communication cable from the battery COM port to the inverter's BMS port, verify the pin order against the manual, and select the correct lithium/CAN protocol on the inverter.
  2. Restart both units.

Source: deye-rw-l2.5a-user-manual-en.pdf, p.10 · rw-f16-manual.pdf, p.10 · rw-l10-2-manual.pdf, p.10 · +6 more official manuals

GB-A HV Battery

BatteryFault

Also applies to:GB-A

What it means

MBMS_SAM_SIG_ID_PCS_ERROR_STATE — The PCS RS485 communication fails (PCS error state signal).

Cause: The battery stopped receiving valid RS485 communication from the PCS, or the PCS is signalling an error state.

How to fix it

  1. Check the RS485 cable and pinout to the PCS and clear any fault on the PCS side, then restart.
  2. Contact Deye support if it persists.

Source: gb-a-pack6-gb-a4-gb-a10-gb-a16-manual.pdf, p.13

Frequently asked questions

What does error 31 mean on a DEYE inverter?
It depends on the model — 10 devices use code 31. On the SUN G01P3-EU-BM8 Series it means: Relay open circuit fault. The card for each model on this page gives its exact meaning and fix.
Is error 31 a fault or a warning?
31 is a fault code: the inverter cuts its output and the red LED stays solid until it is cleared.
How do I clear or fix error 31?
1. Check the relays and their driver signals. The exact steps for each affected model are listed on this page.

Related error codes

Other codes on the SUN G01P3-EU-BM8 Series

All SUN G01P3-EU-BM8 Series codes

Other codes on the SUN G02P1-EU Series

All SUN G02P1-EU Series codes

Other codes on the SUN G03/G01P3-AM8 Series

All SUN G03/G01P3-AM8 Series codes

Other codes on the SUN G04/G05/G06 3-Phase

All SUN G04/G05/G06 3-Phase codes All SUN G06P3-EU Series codes

Other codes on the SUN G04P1/G05P1 Series

All SUN G04P1/G05P1 Series codes

Other codes on the SUN SG01HP3/SG02HP3 Hybrid

All SUN SG01HP3/SG02HP3 Hybrid codes

Prefer the full written guide? Read the complete DEYE inverter error-code guide

Compiled from official DEYE user manuals. Always consult your device manual and a qualified technician before performing repairs.