Saunier Duval
Saunier Duval Water Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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F0
Water heater does not start, display shows F0 immediately after power-up
Control board configuration / parameter fault
F1
Water heater attempts to start but shuts down with F1, no flame established
Ignition failure / no flame detection
F10
F10 error: the water heater does not start, often after power issues.
Low or Unstable Mains Voltage / Power Supply Fault
F11
F11 displayed; the fan runs, but the ignition sequence does not proceed correctly.
Gas Valve Control / Modulation Fault
F12
F12 appears intermittently, especially during high demand; the unit shuts down.
Water Circulation / Pump Fault (on models with pump or recirculation)
F13
F13 error: the unit may start then quickly shut down, sometimes with gurgling noises.
Condensate Drainage Fault (Condensing Models)
F14
F14 displayed; the unit fails to ignite or shuts down with a gas-related alarm.
Gas Type / Combustion Configuration Fault
F15
F15 error, often associated with very high or very low outlet temperatures.
Overtemperature or temperature differential fault.
F16
F16 displayed, burner shuts down, sometimes with a yellow or unstable flame.
Flame quality / ionization fault.
F17
F17 error, unit fails to detect flame despite ignition sparks.
Flame detection circuit fault.
F18
F18 displayed, unit may start and stop repeatedly, and temperature fluctuates.
Modulation / power control fault.
F19
F19 error, often during low-flow operation, with water temperature too high.
Minimum power / low-flow overheat fault.
F2
Unit locks out with F2 shortly after ignition, burner shuts down
Flame loss during operation
F20
F20 displayed, unit shuts down on high-temperature alarm.
Primary circuit overheat.
F21
F21 error, unit does not start, sometimes after sensor replacement.
Sensor configuration / mismatch fault.
F22
F22 displayed, no ignition, often after a water supply interruption.
Low water pressure / dry fire protection.
F23
F23 error, unit may start then quickly shut down, sometimes with loud boiling noises.
Flow/return temperature differential too high.
F24
F24 displayed, unit refuses to start, sometimes after PCB replacement.
Internal communication / PCB fault.
F3
Water heater displays F3 and will not ignite, often after overheating event
Safety temperature limiter (overheat thermostat) tripped or open circuit
F4
Display shows F4, fan does not start or stops unexpectedly, no ignition
Fan / air pressure system fault
F5
Unit locks out with F5, often accompanied by a noisy fan or poor combustion.
Flue Gas Evacuation / Air Pressure Switch Fault
F6
Display shows F6; the water heater does not start, often after sensor wiring work.
Flow Sensor / Flow Switch Fault
F7
F7 appears; water temperature is unstable, or the unit shuts down shortly after ignition.
Primary NTC Temperature Sensor Fault
F8
F8 error: domestic hot water temperature reading is erratic or implausible.
DHW Outlet NTC Sensor Fault
F9
F9 displayed; the unit may overheat or shut down unexpectedly.
Return Temperature Sensor / Secondary NTC Fault
Symptom
Water heater causes condensation or damp patches on nearby walls or ceiling.
Flue gas or steam leakage.
Symptom
Water heater display works, but buttons or knobs do not respond.
User interface / control panel fault.
Symptom
Water heater does not start at all; no lights or display.
No power / Electrical supply failure
Symptom
Water heater emits a burning or plastic smell during operation.
Overheating of electrical or plastic components.
Symptom
Water heater emits a smell of gas around the appliance.
Gas leak at appliance
Symptom
Water heater emits a whistling or high-pitched noise when running.
Gas flow resonance / Burner noise
Symptom
Water heater frequently cycles on and off while a tap is open.
Short cycling / unstable operation.
Symptom
Water heater has power but does not ignite when a hot water tap is opened.
No demand recognition / Flow detection failure
Symptom
Water heater ignites but hot water is lukewarm or not hot enough.
Insufficient heating / Low outlet temperature
Symptom
Water heater leaks from the flue or top of the unit, especially on condensing models.
Condensate leakage / Flue condensation issue
Symptom
Water heater leaks water from the bottom of the casing.
Internal water leak
Symptom
Water heater makes loud banging or knocking noises during operation.
Kettling / Boiling in heat exchanger
Symptom
Water heater produces very hot water, risk of scalding, temperature difficult to control.
Overheating / Poor temperature regulation
Symptom
Water heater trips the household circuit breaker or RCD when starting.
Electrical short or earth leakage.
Symptom
Water heater vibrates excessively or rattles during operation.
Mechanical vibration / Mounting fault
Symptom
Water heater works, but hot water temperature fluctuates significantly during a shower.
Unstable outlet temperature.
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| F0 |
Water heater does not start, display shows F0 immediately after power-up
|
Control board configuration / parameter fault | View Details |
| F1 |
Water heater attempts to start but shuts down with F1, no flame established
|
Ignition failure / no flame detection | View Details |
| F10 |
F10 error: the water heater does not start, often after power issues.
|
Low or Unstable Mains Voltage / Power Supply Fault | View Details |
| F11 |
F11 displayed; the fan runs, but the ignition sequence does not proceed correctly.
|
Gas Valve Control / Modulation Fault | View Details |
| F12 |
F12 appears intermittently, especially during high demand; the unit shuts down.
|
Water Circulation / Pump Fault (on models with pump or recirculation) | View Details |
| F13 |
F13 error: the unit may start then quickly shut down, sometimes with gurgling noises.
|
Condensate Drainage Fault (Condensing Models) | View Details |
| F14 |
F14 displayed; the unit fails to ignite or shuts down with a gas-related alarm.
|
Gas Type / Combustion Configuration Fault | View Details |
| F15 |
F15 error, often associated with very high or very low outlet temperatures.
|
Overtemperature or temperature differential fault. | View Details |
| F16 |
F16 displayed, burner shuts down, sometimes with a yellow or unstable flame.
|
Flame quality / ionization fault. | View Details |
| F17 |
F17 error, unit fails to detect flame despite ignition sparks.
|
Flame detection circuit fault. | View Details |
| F18 |
F18 displayed, unit may start and stop repeatedly, and temperature fluctuates.
|
Modulation / power control fault. | View Details |
| F19 |
F19 error, often during low-flow operation, with water temperature too high.
|
Minimum power / low-flow overheat fault. | View Details |
| F2 |
Unit locks out with F2 shortly after ignition, burner shuts down
|
Flame loss during operation | View Details |
| F20 |
F20 displayed, unit shuts down on high-temperature alarm.
|
Primary circuit overheat. | View Details |
| F21 |
F21 error, unit does not start, sometimes after sensor replacement.
|
Sensor configuration / mismatch fault. | View Details |
| F22 |
F22 displayed, no ignition, often after a water supply interruption.
|
Low water pressure / dry fire protection. | View Details |
| F23 |
F23 error, unit may start then quickly shut down, sometimes with loud boiling noises.
|
Flow/return temperature differential too high. | View Details |
| F24 |
F24 displayed, unit refuses to start, sometimes after PCB replacement.
|
Internal communication / PCB fault. | View Details |
| F3 |
Water heater displays F3 and will not ignite, often after overheating event
|
Safety temperature limiter (overheat thermostat) tripped or open circuit | View Details |
| F4 |
Display shows F4, fan does not start or stops unexpectedly, no ignition
|
Fan / air pressure system fault | View Details |
| F5 |
Unit locks out with F5, often accompanied by a noisy fan or poor combustion.
|
Flue Gas Evacuation / Air Pressure Switch Fault | View Details |
| F6 |
Display shows F6; the water heater does not start, often after sensor wiring work.
|
Flow Sensor / Flow Switch Fault | View Details |
| F7 |
F7 appears; water temperature is unstable, or the unit shuts down shortly after ignition.
|
Primary NTC Temperature Sensor Fault | View Details |
| F8 |
F8 error: domestic hot water temperature reading is erratic or implausible.
|
DHW Outlet NTC Sensor Fault | View Details |
| F9 |
F9 displayed; the unit may overheat or shut down unexpectedly.
|
Return Temperature Sensor / Secondary NTC Fault | View Details |
| – |
Water heater causes condensation or damp patches on nearby walls or ceiling.
|
Flue gas or steam leakage. | View Details |
| – |
Water heater display works, but buttons or knobs do not respond.
|
User interface / control panel fault. | View Details |
| – |
Water heater does not start at all; no lights or display.
|
No power / Electrical supply failure | View Details |
| – |
Water heater emits a burning or plastic smell during operation.
|
Overheating of electrical or plastic components. | View Details |
| – |
Water heater emits a smell of gas around the appliance.
|
Gas leak at appliance | View Details |
| – |
Water heater emits a whistling or high-pitched noise when running.
|
Gas flow resonance / Burner noise | View Details |
| – |
Water heater frequently cycles on and off while a tap is open.
|
Short cycling / unstable operation. | View Details |
| – |
Water heater has power but does not ignite when a hot water tap is opened.
|
No demand recognition / Flow detection failure | View Details |
| – |
Water heater ignites but hot water is lukewarm or not hot enough.
|
Insufficient heating / Low outlet temperature | View Details |
| – |
Water heater leaks from the flue or top of the unit, especially on condensing models.
|
Condensate leakage / Flue condensation issue | View Details |
| – |
Water heater leaks water from the bottom of the casing.
|
Internal water leak | View Details |
| – |
Water heater makes loud banging or knocking noises during operation.
|
Kettling / Boiling in heat exchanger | View Details |
| – |
Water heater produces very hot water, risk of scalding, temperature difficult to control.
|
Overheating / Poor temperature regulation | View Details |
| – |
Water heater trips the household circuit breaker or RCD when starting.
|
Electrical short or earth leakage. | View Details |
| – |
Water heater vibrates excessively or rattles during operation.
|
Mechanical vibration / Mounting fault | View Details |
| – |
Water heater works, but hot water temperature fluctuates significantly during a shower.
|
Unstable outlet temperature. | View Details |
No matching codes found
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