
STATE 474
RCMU sensor faulty
Some models: Short circuit between DC connection and ground (external insulation fault)
Some models: High ohm resistor for solar module ground is defective
Behaviors
Inverter does not feed current into the grid.
Status Code Class 4
Class 4 status codes (state codes that start with a four, i.e., 4xx), typically necessitate intervention by a Fronius-trained service technician.
STATE 474 applies to:

Primo

Symo

CL
Solutions for this Error
Remedies
- Check DC cables at the inverter and ensure DC disconnects are in the ON position. Measure DC voltage, polarity, and isolation at the inverter clamps (Qualified Techs only).
- If this issue persists, the next steps include inspecting internal inverter components and their cabling by a trained Fronius Service Provider to further diagnose this specific issue. Defective components or the device itself may need to be replaced.
Get Help with this Error:
The best point of contact is your original installer
If the orginal installer is no longer available, contact a local Fronius Service Provider
DENVER RESIDENTS: Is your system located in the Denver, CO metro area? CONTACT US