State Water Heater E74 Error Code — What It Means
An E74 error code is not officially documented for State brand water heaters in available manufacturer literature. State water heaters (manufactured by A. O. Smith) typically use a different fault code system, and E74 may be a misread display, a code from a different brand, or a code specific to a very new or specialized model not yet widely documented. Before proceeding, confirm the exact alpha-numeric sequence shown on your unit’s display and locate your model and serial number on the rating plate, usually found on the front or side of the tank. Cross-reference the code with the troubleshooting chart printed inside the access panel or in your owner’s manual.
Common Causes
- Misread or transposed display code The actual code may be a similar-looking fault such as E04, E14, or E54, which are documented State codes for different sensor or ignition faults.
- Thermostat or control system from another device E74 is a known Nest thermostat error (no power to RH wire), which homeowners sometimes confuse when troubleshooting multiple systems at once.
- Undocumented code on a new or commercial model Some commercial or very recent residential State models may use codes not yet published in widely available service literature.
- Aftermarket or third-party control board If the control board was previously replaced with a non-OEM part, the fault code set may differ from factory State codes.
Step-by-Step Fix
- Photograph the display and rating plate. Capture a clear image of the exact code shown and the model/serial tag so you can reference both when consulting State support or a technician.
- Power-cycle the water heater. Turn off the circuit breaker for two minutes, then restore power to clear transient faults and confirm the code reappears consistently.
- Locate your owner’s manual or service guide. Check the troubleshooting section inside the front access panel or download the manual from the State Water Heaters website using your full model number.
- Cross-reference the code. Compare E74 against every code listed in your manual; if it does not appear, note the closest match and its recommended diagnostic steps.
- Inspect all wire connections at the control board. Look for loose, corroded, or burned terminals on the gas valve, thermostors, and flame sensor leads.
- Contact State technical support. Call 1-800-365-0024 with your model number, serial number, and the exact code to obtain official guidance or confirm whether E74 applies to your unit.
- Document the fault history. Write down how often the code appears, what operating mode triggers it, and any recent service work to help a technician diagnose faster.
Parts Often Needed
| Part | Notes |
|---|---|
| State OEM Gas Control Valve Assembly | Amazon | Only if State support confirms the code relates to valve logic; must match your model and gas type. |
| State OEM Electronic Control Board | Amazon | Required if the display or code set has failed; verify board part number from your serial-number range. |
When to Call a Pro
Call a licensed plumber or water-heater technician immediately if you cannot find E74 in your manual, if the code appears alongside other symptoms like gas odor or no hot water, or if you are uncomfortable working with gas appliances and 120V or 240V electric connections. A technician with access to State service bulletins can decode proprietary fault codes and has the tools to test gas-valve logic boards and thermistor circuits safely. Many E-series codes require voltage and resistance measurements that are difficult without a multimeter and wiring diagram.