A. O. Smith E55 Code: Leak Alert on an Electric Heater
On this page (5 sections)
The Short Answer: On A. O. Smith-built electric heaters with a leak sensor, E55 is commonly reported as a water-leak alert, and the control stops heating. We could not confirm the code in A. O. Smith’s published manuals, so check your model’s label or manual. Either way, look for water: if the sensor is wet, find the source before resetting anything. Most leaks are at fittings, not the tank.
Confirm what E55 means on your model
Leak detection is built into several A. O. Smith-made heaters, and code numbers differ between product lines. On A. O. Smith’s newer smart heat pump models, for example, the use and care guide (opens in a new tab) lists 031 as “water leak,” not E55. So read the code chart on the heater, check the manual in the pocket on the tank, or find it with A. O. Smith’s manual lookup (opens in a new tab). A. O. Smith’s technical assistance line is 1-800-527-1953.
If E55 does turn out to be something other than a leak alert on your model, follow that meaning instead. The steps below still apply whenever there is water around the heater.
Find where the water is coming from
Dry everything with towels, wait a few minutes, and look again. A. O. Smith’s technical bulletin on puddles (opens in a new tab) makes the same point: most water around a heater comes from connections and other sources, not the tank itself.
| Where you find water | Likely source | What it usually means |
|---|---|---|
| Drips at the drain valve near the bottom | Drain valve not fully closed or worn | Minor repair; see plastic drain valve dripping |
| Coming out of the relief valve pipe | High pressure, overheating, or a worn relief valve | Needs a plumber; never cap the pipe |
| Running down from pipes on top | Inlet or outlet fitting, connector, or valve | Fitting repair |
| Around a lower access panel | Element gasket, or a tank leak behind it | Technician to tell the two apart |
| From under the jacket, rust stains, no fitting wet | Tank | Replacement |
| In the pan, heater dry | Another appliance, condensation, or an overhead pipe | Not the heater |
| Sensor wet, nothing else | Splash from a recent repair, or condensation | Dry and monitor |
When it is safe to reset
If you found a clear one-off cause, such as a splash during a repair or a drain valve you have closed fully, dry the sensor and the floor completely. Then follow the reset steps in your manual; on many digital controls that means switching the breaker off and on. If the code returns, or water keeps appearing, leave the breaker off.
Do not unplug, bypass, or move the leak sensor so the heater keeps running. It is there to stop a 240-volt heater from operating while water is collecting.
What the plumber will check
The plumber traces the leak to its source, checks house water pressure and the thermal expansion tank if the relief valve is discharging, and inspects the element gaskets. Fittings, valves, connectors, and gaskets are repairs. A leak from the tank shell is not repairable and means a new heater. Our guides on leaking from the bottom of the tank and whether you can still use water when the heater is leaking cover the next steps.
Frequently Asked Questions
Q: The sensor shows E55 but I can’t find any water. What now? A: Check the pan and floor directly under the sensor, behind the heater, and above it for condensation dripping from cold pipes. If everything is dry and the code returns after a reset, the sensor or its wiring may be faulty; a technician can test it.
Q: Will the heater keep working if I leave E55 showing? A: Not normally. Leak alerts usually stop heating until cleared, and on some models a separate valve shuts off the water supply. Check your manual.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- A. O. Smith: model and manual lookup (opens in a new tab)Find the instructions for the model on your rating plate; this directory does not verify a particular error-code meaning.
- A. O. Smith technical bulletin 51: puddles around a heater (opens in a new tab)Common water-leak sources and the distinction between fittings and a failed tank.
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