Water heater fault codes

A.O. Smith water heater faults: fault codes, causes and parts (page 2 of 2)

Codes 151 to 231 of the 231 fault codes for A.O. Smith. Looking for a specific code? Use the search on the first page.

A.O. Smith water heater fault codes 151 to 231 of 231

The code list is split over 2 pages. Looking for a specific code? Use the search on the first page: it searches all 231 codes in one go.

Code	Cause
Insufficient / no hot water	There is no hot water left.
Insufficient / no hot water	The control is in OFF mode.
Insufficient / no hot water	The temperature (Tset) is set too low.
Insufficient / no hot water	The boiler has been switched off
Insufficient / no hot water	There is no supply voltage
Insufficient / no hot water	There is no hot water left
Insufficient / no hot water	The control is in OFF mode
Insufficient / no hot water	The control is in the OFF position.
Insufficient / no hot water	Temperature (Tset) is set too low.
Insufficient / no hot water	Appliance is switched off
Insufficient / no hot water	No supply voltage present
Insufficient / no hot water	Hot water supply is exhausted
Insufficient / no hot water	The control is in the OFF position
Insufficient / no hot water	Temperature (Tset) is set too low
S01	Sensor is not (properly) connected.
S01	Defective flue gas sensor
S01	Broken cable
S01	Sensor T2 is not (properly) connected
S01	Broken cable and/or defective sensor T2
S02	Sensor T1 is not (properly) connected
S02	Broken cable and/or defective sensor T1
S02	Sensor is not (properly) connected
S02	Defective sensor
S02	Broken cable
S03	Sensor is not (properly) connected
S03	Defective sensor
S03	Broken cable
S03	Broken cable and/or defective sensor
S04	Flue gas sensor is not (properly) connected.
S04	Defective flue gas sensor
S04	Broken cable
S04	Dummy is not (properly) connected
S04	Defective dummy
S05	Dummy is not (properly) connected
S05	Defective dummy
S05	Flue gas sensor is not (properly) connected.
S05	Defective flue gas sensor
S05	Broken cable
S11	Short circuit in sensor circuit
S12	Short circuit in sensor circuit
S13	Short circuit in sensor circuit
S14	Short circuit in sensor circuit
S14	Short circuit in flue gas sensor circuit
S15	Short circuit in flue gas sensor circuit
S15	Short circuit in sensor circuit
Water leak	Water is leaking from a threaded water connection.
Water leak	Condensate leak
Water leak	Another boiler or pipe section nearby is leaking.
Water leak	The boiler tank is leaking.
Water leak	The boiler tank is leaking
Water leak	Leak at a water connection (threaded)
Water leak	Leak from another water appliance or pipe nearby
Water leak	Leak from the tank of the appliance
Water leak	Condensate
X45-XXXX	(Lockout) Sensor fault - Short circuit of the temperature sensor: Short circuit in the sensor circuit.
X46-XXXX	(Lockout) Sensor fault - Short circuit of temperature sensor: Short circuit in the sensor circuit.
X47–XXXX	(Lockout) Sensor fault - Open circuit of temperature sensor: Sensor is not (correctly) connected.
X47–XXXX	(Lockout) Sensor fault - Open circuit of temperature sensor: Damaged wiring and/or defective sensor.
X48-XXXX	(Lockout) Sensor fault - Open circuit of temperature sensor: Sensor is not (correctly) connected.
X48-XXXX	(Lockout) Sensor fault - Open circuit of temperature sensor: Damaged wiring and/or defective sensor.
X54-XXXX	Temperature warning: The temperature in the tank is higher than 90 ºC.
X57-XXXX	(Lockout) Short circuit of the flame sensor: Electrical connection between the flame sensor and the tank or burner.
XA5-XXXX	(Lockout) Temperature fault - The temperature limit has been exceeded: The temperature in the tank is above 95 ºC.
XAC-XXXX	(Lockout) Air pressure switch fault - The switch is not closed when the fan is running during pre-purge: The tubes are damaged.
XAC-XXXX	(Lockout) Air pressure switch fault - The switch is not closed when the fan is running during pre-purge: The wiring is damaged.
XAC-XXXX	(Lockout) Air pressure switch fault - The switch is not closed when the fan is running during pre-purge: Air leak between the venturi and the air connection.
XAC-XXXX	(Lockout) Air pressure switch fault - The switch is not closed when the fan is running during pre-purge - Insufficient pressure difference in the air pressure switch, caused by: - the air supply and flue gas discharge system - condensate drain fault - fouled burner - blocked heat exchanger
XAC-XXXX	(Lockout) Fan fault - The switch is closed when the fan is not running: Damaged wiring/closed circuit.
XAC-XXXX	(Lockout) Fan fault - The switch is closed when the fan is not running: Air pressure switch defective.
XAC-XXXX	(Lockout fault) Air pressure switch fault - The switch is not closed when the fan is running during pre-purge - Insufficient pressure difference in the air pressure switch, caused by: - the air supply and flue gas discharge system - condensate drain fault - dirty burner - blocked heat exchanger.
XAF-XXXX	(Lockout) Control fault - Hardware fault: Too many resets.
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: No gas
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: Air in the gas pipes.
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: Fault in the spark igniter circuit.
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: Fault in ionisation circuit.
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: Supply voltage too low.
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: The bent ionisation probe is touching a metal surface.
XB2-XXXX	(Lockout) Ignition fault - Three failed ignition attempts: The ceramic part of the ionisation probe is broken or cracked.
XB2-XXXX	(Lockout fault) Ignition fault Three failed ignition attempts: No gas
XC9-XXXX	(Lockout) Control fault - Hardware fault: Disconnect the selection knob.
XXX	Internal fault message from the control.

A.O. Smith parts are available from Instalpunt. Back to the first page with the most searched codes and frequently asked questions.