What does the Fronius STATE 604 error code mean?

The STATE 604 is a status code that means dc module temperature sensor faulty. For full troubleshooting steps, click here .

What is a STATE code on a Fronius inverter?

A STATE code is an internal diagnostic status displayed on Fronius inverters when a fault or condition is detected. Each code corresponds to a specific behavior or issue, and is used to aid in troubleshooting and maintenance.

Can I reset a Fronius STATE error code myself?

Some STATE codes clear automatically when the issue is resolved, such as after a grid fluctuation. Others may require a manual restart or service intervention. Always review the recommended solutions before attempting a reset.

Do I need to call an installer or technician for STATE code errors?

It depends on the error. Some STATE codes relate to grid voltage fluctuations or minor issues, while others may indicate wiring faults, insulation problems, or internal hardware failures. If you're unsure, or the error persists, contact your installer or a qualified service provider.

Where can I find support for Fronius inverter STATE codes?

Visit the Fronius Service Provider Finder to locate a trained technician near you. If you’re in the Denver, Colorado area, Paragon Solar offers expert Fronius inverter support.

STATE 604

DC module temperature sensor faulty

The temperature sensor on the DC power module is not providing valid readings, impairing the inverter’s ability to monitor and manage thermal conditions for safe operation.

galvo

primo

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Expected Behaviors

The inverter is displaying a STATE 604 message with a red or amber LED. Feed-in to the grid has been temporarily interrupted. The inverter will re-enter the startup phase and, if all self-tests pass, will resume normal operation automatically.

State Class

A state class is a generalized description of errors, catagorized by the number the STATE code starts with.

Class 6 Status: Peripheral Communication & Integration Faults
These codes relate to communication problems with external components like sensors, dataloggers, or expansion modules. They may reduce functionality but usually do not stop power generation. If they persist, inspection by a Fronius Trained Service Partner is recommended to verify wiring, compatibility, and component health.

Fronius inverters in the U.S. typically come with a standard 10-year warranty. Starting in 2024, registering the inverter on the Fronius Solar.web website (the Fronius solar monitoring platform), extended the warranty by an additional 2 years, totaling 12 years of coverage, and updates the warranty start date to the actual installation date. Fronius has also offered warranty extensions of up to 20 years.

The inverter label, typically located on the bottom of the unit, lists the device serial number. To check if your inverter is still covered, call Fronius Technical Support at 1-877-Fro-nius (1-877-376-6487)

Founded in 1945 by Günter Fronius in Pettenbach, Austria, Fronius began as a repair shop for radios and electrical equipment. Recognizing the need for efficient battery charging, Günter developed a device to recharge car batteries, marking the company's first foray into energy solutions. Read More

In the 1950s, Fronius expanded into welding technology, introducing the first welding transformer with magnet-yoke control in 1950. This innovation allowed for continuous adjustment of welding current, setting the stage for future advancements in welding systems.

The company's commitment to innovation led to the development of the Transarc 500 in 1981, the world's first primary transistor-based inverter welding system, which significantly reduced power consumption. Fronius has since expanded into advanced welding automation recognized among key players in the industry, alongside firms like ABB, and Yaskawa Electric Corporation. Their current offerings include robotic welding systems, collaborative robots (cobots), and intelligent software solutions like Fronius Pathfinder, which provides functions for creating and simulating welding sequences.

In 1992, Fronius ventured into photovoltaics, releasing its first photovoltaic inverter, the Fronius Sunrise, in 1995. This move marked the beginning of Fronius's Solar Energy division, which has since become a cornerstone of the company.

Subsequent innovations include the IG inverter series in 2001, the SnapINverter technology in 2014, and the GEN24 Plus hybrid inverter in 2020, reflecting Fronius's ongoing commitment to advancing solar technology.

Today, Fronius stands as one of the top-tier inverter manufacturers globally, often ranked alongside SMA (Germany), in terms of quality and market presence. While companies like Enphase dominate the U.S. microinverter space and SolarEdge leads in optimizer-based MLPE systems, Fronius remains a leading choice for high-efficiency string inverter systems, particularly in Europe, Australia, and commercial U.S. installations. Their inverters have robust build quality, excellent thermal performance (with active cooling), long warranties, and strong service support. With over 3.4 million inverters installed and more than 35 TWh of clean energy produced, Fronius competes head-to-head with larger players, maintaining a presence in premium residential and commercial markets globally.

The best point of contact is your original installer
If the orginal installer is no longer available, contact a local Fronius Service Provider in your area.

Fronius Technical Support can also be reached at 1-877-Fro-nius (1-877-376-6487)

DENVER RESIDENTS: Is your system located in the Denver, CO metro area? CONTACT US

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