A.O. Smith EEU6-50H45DV Water Heater Problems & Error Codes — Overview
The EEU6-50H45DV is a 50-gallon residential electric water heater from A.O. Smith running on 240V with two 4,500-watt copper heating elements and an electronic control with standard and vacation modes. This model does not have a published error code table in readily available documentation, so if you see a fault code on the display, scan the QR code on the rating plate to pull the exact manual for your serial number. Most service calls on electric tanks like this one trace back to tripped limits, failed thermostats, open elements, or loose connections rather than control board faults.
Most Common Problems on This Model
- No hot water and display is off or blank Check the breaker and verify 240V at the unit supply terminals, then inspect the disconnect and internal wiring for burned connections or an open circuit.
- No hot water but unit has power The high-limit cutoff on the upper thermostat has tripped due to overheating or a stuck lower thermostat, press the red reset button after the tank cools and verify the lower thermostat is operating correctly.
- Water is warm but not hot enough One of the two 4,500-watt heating elements has failed open or the corresponding thermostat is not closing, test both elements for continuity and replace the faulty one.
- Breaker trips repeatedly when heater calls for heat A heating element has shorted to the tank wall or a terminal connection has arced and is drawing excess current, disconnect power and ohm-test each element to ground before replacing.
- Display shows a fault code Use the QR code on the rating plate to download the model-specific manual and look up the exact code, most codes point to a sensor fault or control wiring issue on the electronic board.
- Upper element heats but lower element does not The upper thermostat is not transferring power to the lower thermostat or the lower thermostat itself has failed, test and replace the defective thermostat.
- T&P valve discharges water or steam Tank temperature or pressure has exceeded safe limits due to a stuck thermostat or failed high-limit, shut off power immediately and replace the faulty thermostat and the T&P valve.
- Heater cycles on and off too frequently Thermostat differential is incorrect or a thermostat is failing intermittently, replace the upper and lower thermostats as a matched set to restore proper cycle timing.
Parts That Commonly Fail
| Part | Notes |
|---|---|
| Upper thermostat and high-limit assembly | Amazon | Includes the red reset button and controls sequencing to the lower element |
| 4,500-watt heating elements (copper) | Amazon | Upper and lower, 240V, replace both if one has failed and tank is older than 5 years |
| Lower thermostat | Amazon | Controls the lower element and receives power transfer from the upper thermostat |
| Electronic control board and display | Amazon | Manages vacation mode and fault reporting, verify all other components first before replacing |
Water-Heater Error Codes for This Model
These codes apply to this model line:
- A O Smith Water Heater E2 error code
- A O Smith Water Heater E4 error code
- A O Smith Water Heater E6 error code
When to Call a Pro
Call a licensed electrician or plumber if you are not comfortable working with 240-volt power, if you see burned or melted wire insulation inside the junction box, or if the breaker continues to trip after you have replaced elements and thermostats. Any work inside the access panels requires the breaker to be off and locked out, and you must verify zero voltage at all terminals before touching any wires. If the T&P valve is discharging or the tank is leaking from the shell, shut off power and water immediately and call a pro to evaluate whether the tank needs replacement. For gas line, burner, or igniter work, or if you ever smell gas, stop and call a licensed technician.