Expanded exact-code directory
AO Smith gas water heater error codes
AO Smith gas water heater codes as A. O. Smith lists them, each with its meaning and the first safe check.
- 1 flashNormal operation: a bright and dim heartbeat.
- 2 flashesThe thermopile voltage is low.
- 4 flashesThe temperature was exceeded and the energy cut-off
- 8 flashesPower off failure. The handbook's check depends on
AO Smith gas water heater code 0 flashes (light not lit): meaning and exact next steps
0 flashes (light not lit) means The control is off or the pilot is out.
Open record AO Smith gas water heater · exact codeAO Smith gas water heater code 5 flashes: meaning and exact next steps
5 flashes means Sensor failure, which A. O. Smith lists for the temperature sensing inside the gas control.
Open record AO Smith gas water heater · exact codeAO Smith gas water heater code 7 flashes: meaning and exact next steps
7 flashes means Internal control failure, which A. O. Smith lists when the gas control finds a fault in its own electronics.
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Every AO Smith gas water heater code: what it means and what to do
AO Smith gas water heater code 1 flash
Normal operation: a bright and dim heartbeat.
Nothing is wrong when the light shows one flash.
A. O. Smith's handbook lists no corrective action for a single flash because it is the normal heartbeat.
AO Smith gas water heater code 2 flashes
The thermopile voltage is low.
Look for loose or damaged wires at the gas control without disturbing the gas connections.
A. O. Smith's steps: check all wiring connections for loose or damaged wires and correct them, then check the millivolt output of the thermopile, and if the output is less than 350 millivolts DC, replace the thermopile. The handbook also refers to its Condensation section for this code.
AO Smith gas water heater code 4 flashes
The temperature was exceeded and the energy cut-off (ECO) activated.
Turn the gas control thermostat knob to OFF.
A. O. Smith's steps: turn the gas control valve and thermostat knob to OFF, turn the main gas supply OFF, and replace the gas control valve and thermostat. Replacing a gas control is for a qualified technician.
AO Smith gas water heater code 8 flashes
Power off failure. The handbook's check depends on whether the pilot flame is still present with the control knob at OFF.
Note whether the pilot flame is present when the control knob is set to OFF.
A. O. Smith says that if the pilot flame is present with the knob at OFF, replace the gas control valve and thermostat. If the pilot flame is not present with the knob at OFF, wait 10 minutes for the thermopile to cool and relight the unit, and if the condition returns, replace the gas control valve and thermostat.
AO Smith gas water heater code Solid light
The pilot was recently extinguished and the thermopile is cooling down.
Turn the gas control thermostat knob to OFF and wait 10 minutes.
A. O. Smith says to wait 10 minutes for the thermopile to cool, then relight following the label instructions. The gas control has circuitry that requires waiting 10 minutes between lighting attempts. Until the thermopile reaches normal operating temperature the status light will not blink even if the pilot is lit, which can take up to 90 seconds of continuous pilot operation.