Brand guide
All A. O. Smith water heater guides
Choose the symptom or code that matches your unit. Confirm the exact model and control generation against the rating plate before following model-specific instructions.
AO Smith Blinking Green Light Codes
A slow green blink on an A. O. Smith gas valve is often normal. Two or more flashes is a fault code. How to count the pattern and read it.
Pilot and ignition problemsAO Smith Blinking White Light
A white or pale LED blinking on an A. O. Smith gas valve can be normal, a call for heat, or a lockout. How to tell them apart from the count.
Error codes and flashing lightsAO Smith E02 Code: High-Limit Trip
E02 on an A. O. Smith Energy Smart electric tank is a high-limit (ECO) trip. Why it happens, when one reset is reasonable, and when it isn't.
Leaks and floodingAO Smith E55 Code: Leak Detected
E55 on an A. O. Smith Energy Smart tank means the leak sensor found water. Shut off power, find the wet part, and learn when the tank is done.
Pilot and ignition problemsAO Smith Gas Control Valve Problems
A. O. Smith gas control faults usually come from a weak thermocouple or thermopile, an LED lockout, a clogged FVIR screen, or a failed valve.
Pilot and ignition problemsAO Smith Gas Water Heater Reset Keeps Tripping
An AO Smith gas reset that trips again points to venting, flame, or a failing control. Stop resetting.
No hot waterAO Smith Hybrid Problems: Codes
A. O. Smith Voltex hybrid not heating? Common causes are a dirty filter, vacation mode, an element or ECO fault, a compressor code, or a leak.
Pilot and ignition problemsAO Smith Igniter Not Working
An A. O. Smith that won't light often has a hot-surface igniter that never glows, a control lockout, or no 120 V. How to narrow it down.
Leaks and floodingAO Smith Leaking From the Bottom
Water under an A. O. Smith can come from the drain valve, T&P discharge, a fitting, an element gasket, or the tank. How to find the source.
Error codes and flashing lightsAO Smith Tankless Reset Button
Most A. O. Smith tankless units reset by cycling 120 V power, not a hidden button. When one reset is safe, and when a code or gas smell means stop.
Error codes and flashing lightsAO Smith Tankless Water Heater Troubleshooting
An AO Smith tankless that is cold needs a code, flow, power, gas, or vent check. Photograph the display.
No hot waterAO Smith Tankless With No Hot Water
An A. O. Smith tankless with no hot water usually has no 120 V, no flow signal, a lockout code, or no gas. Read the display before resetting.
Error codes and flashing lightsAO Smith Water Heater Blinks 3 Times
Three flashes on an A. O. Smith means different faults on electric, power-vent, and atmospheric models: thermistor, pressure switch, or other.
Pilot and ignition problemsAO Smith Water Heater Humming Noise
An A. O. Smith humming can be a transformer, element, gas valve solenoid, or hybrid compressor. Match the sound to when it happens.
TroubleshootingAO Smith Water Heater Troubleshooting
A. O. Smith troubleshooting by product: gas, power-vent, Energy Smart electric, Voltex hybrid, or tankless. Identify yours, then follow its checks.
No hot waterNew AO Smith Electric Not Heating
A new AO Smith electric that is ice-cold is fill, 240 V, ECO, or an install miss. Do not dry-fire it.