74Fault

Felicity inverter error 74 (F74)

INV Relay self check fault

Also displayed as F74 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:

IVGM5KL-P1G1

InverterFault

Also applies to:IVGM6KL-P1G1IVGM7K6L-P1G1IVGM8KL-P1G1

What it means

INV Relay self check fault — Inverter relay self-check fault.

Cause: A safety relay inside the inverter has failed self-test or is stuck. The inverter is designed to refuse grid connection in this state, so this is not an issue you can clear with restart cycles.

How to fix it

  1. Restart the system 2~3 times
  2. If the fault still exists, please contact us for help.

Source: Felicitysolar IVGM Series Hybrid inverter Instruction Manual.pdf, p.55

T-REX-50KHP3G01

InverterFault

What it means

Main and auxiliary DSP communication fault — There is an error in the DSP communication, try to upgrade the software.

Cause: Communication has been lost between the inverter and a peripheral device — typically a battery BMS, smart meter, or external monitoring dongle.

How to fix it

  1. Verify the communication cable (CAN/RS485/Modbus) is correctly seated and the right pinout is used.
  2. Check baud rate and protocol settings in both devices match.
  3. Reseat the dongle/comms module.
  4. For BMS comms, confirm the battery is powered on and not in deep-discharge protection.

Source: T-REX-50KHP3G01-user-manual-.pdf, p.48

Frequently asked questions

What does error 74 mean on a Felicity inverter?
It depends on the model — 2 devices use code 74. On the IVGM5KL-P1G1 it means: INV Relay self check fault. The card for each model on this page gives its exact meaning and fix.
Is error 74 a fault or a warning?
74 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 74?
1. Restart the system 2~3 times; 2. The exact steps for each affected model are listed on this page.

Related error codes

Other codes on the IVGM5KL-P1G1

All IVGM5KL-P1G1 codes

Other codes on the T-REX-50KHP3G01

All T-REX-50KHP3G01 codes

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

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