State Water Heater E79 Error — What It Means
E79 does not appear in verified State water heater service documentation or manufacturer fault code lists. This code may be misread from the display, specific to a non-State component (such as a connected thermostat), or present on a rebranded unit that uses a different manufacturer’s control board. State water heaters typically use fault codes in different formats, so confirming the exact model number and re-checking the display is the first step. If your unit shows E79 consistently, the control board may be displaying a code from another brand’s lookup table, or the display itself may be faulty.
Common Causes
- Misread display The code may actually be a different alphanumeric combination that looks like E79 on a dim or dirty screen.
- Wrong brand cross-reference Some State models are manufactured by A.O. Smith or Rheem under private label, and their boards may use a different code set.
- Thermostat or control wiring fault If a smart thermostat or external controller is connected, E79 may refer to a 24 V AC power or wiring issue on that device instead of the water heater itself.
- Control board software mismatch A replacement or updated board may display codes that do not match the original State documentation.
- Faulty display module The LED or LCD panel may be showing corrupted characters due to a failing driver circuit.
- Incorrect manual or lookup The manual in hand may belong to a different model year or series that does not include E79 in its table.
Step-by-Step Fix
- Locate the water heater’s model and serial number on the rating plate (usually on the front or side panel) and write down the full string.
- Power cycle the unit by switching off the circuit breaker or gas valve for 30 seconds, then restore power and observe whether the same code reappears.
- Check the display under good lighting and compare each character carefully against the printed fault table in your owner’s manual or on the inside of the access panel.
- Search for the exact model number on the State Industries website or call State customer service with the model and serial to confirm whether E79 is valid for that heater.
- Inspect any connected thermostat or controller (Nest, Honeywell, or zone panel) for error messages, since some 24 V AC wiring faults display on those screens instead of the water heater.
- Photograph the display and model plate and consult a licensed plumber or HVAC technician who can cross-reference the board part number to identify the correct fault library.
- If no external controller is present and the code persists, consider that the control board may need replacement or reprogramming to match the State fault set.
Parts Often Needed
| Part | Notes |
|---|---|
| Gas valve and control board assembly | Amazon | Order by exact model number if the board is confirmed to be displaying non-State codes. |
| Display module or LED panel | Amazon | Rarely sold separately; usually integrated into the main board. |
When to Call a Pro
Call a licensed plumber or water heater technician if you cannot find E79 in any State documentation after verifying your model number. A pro can identify whether the board is original, cross-reference the part number to the correct fault library, and test control voltage and gas-valve signals with a meter. If the heater is still under warranty, contact State customer support before replacing any parts so you do not void coverage.