Saunier Duval
Saunier Duval Smart Thermostats Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E0
Thermostat shows E0 and cannot connect to the Saunier Duval cloud or mobile app
Cloud Service / Account Error
E1
Thermostat shows E1 and cannot connect to the home Wi‑Fi network
Wi‑Fi Connection Failure
E2
Thermostat shows E2 and mobile app cannot control it remotely, though Wi‑Fi appears connected
Server Communication / TLS Error
E3
Thermostat shows E3 and touch screen or buttons do not respond correctly
User Interface Hardware Error
E4
Thermostat shows E4 and battery icon flashes (for battery-powered models)
Low Battery Voltage
E5
Thermostat shows E5 and backlight flickers or unit restarts randomly
Power Supply Instability
E6
Thermostat shows E6 and cannot save new schedules or settings
Non-Volatile Memory Error
E7
Thermostat shows E7 and geolocation or weather-based functions are disabled
Location / GPS Service Error (App Integration)
E8
Thermostat shows E8 and cannot join the Saunier Duval account due to region mismatch
Region / Country Configuration Error
E9
Thermostat shows E9 and indicates pairing error with Saunier Duval internet gateway or RF bridge
Gateway Pairing Error
F0
Thermostat display shows F0 and boiler does not respond to temperature changes
Internal Sensor Calibration Error
F1
Thermostat shows F1 and cannot read room temperature (dashes or 0°C displayed)
Room Temperature Sensor Open Circuit
F2
Thermostat shows F2 and indicates an abnormally high room temperature or no temperature reading
Room Temperature Sensor Short Circuit
F3
Thermostat shows F3 and cannot control the boiler correctly; heating does not start or stops unexpectedly
Communication Failure with Boiler (eBus/OTBus)
F4
Thermostat shows F4 and cannot detect the wireless receiver or boiler gateway
Radio Link Failure to Wireless Receiver
F5
Thermostat shows F5 and cannot control domestic hot water temperature via the boiler
DHW Control Communication Error
F6
Thermostat shows F6 and schedules or setpoints are not applied to the boiler
Internal Clock / Timekeeping Error
F7
Thermostat shows F7 and cannot detect external temperature for weather-compensated control
Outdoor Sensor Communication Error
F8
Thermostat shows F8 and cannot control the boiler via OpenTherm mode
OpenTherm Protocol Error
F9
Thermostat shows F9 and heating demand is ignored by the boiler
Internal Relay / Output Failure
Symptom
Boiler runs continuously and overheats rooms even when thermostat is set low or off
Boiler Firing Without Thermostat Control
Symptom
Condensation or visible moisture inside thermostat housing
Moisture Ingress Affecting Electronics
Symptom
Room temperature overshoots the setpoint by several degrees before boiler turns off
Poor Temperature Regulation / Overshoot
Symptom
Thermostat backlight or display is very dim and hard to read
Display Illumination Degradation
Symptom
Thermostat calls for heat but boiler does not start (no error code on thermostat or boiler)
Control Signal Not Reaching Boiler
Symptom
Thermostat cannot be paired with the Saunier Duval app (QR code or serial not accepted)
Device Registration Failure
Symptom
Thermostat cannot control individual room zones or underfloor heating manifolds as expected
Zoning / Multi-Zone Control Misconfiguration
Symptom
Thermostat display is completely blank and unresponsive
No Power to Thermostat
Symptom
Thermostat does not detect open windows or does not activate energy-saving features when windows are opened
Open-Window Detection Not Working
Symptom
Thermostat does not follow programmed schedule; heating turns on/off at wrong times
Scheduling / Time Program Fault
Symptom
Thermostat frequently disconnects from Wi‑Fi and goes offline in the app
Intermittent Wi‑Fi Connectivity
Symptom
Thermostat loses all settings and pairing after a power cut
Loss of Non-Volatile Configuration
Symptom
Thermostat or RF receiver becomes very warm to the touch during normal operation
Overheating of Control Unit
Symptom
Thermostat or RF receiver emits a burning smell or visible smoke
Severe Electrical Failure / Overheating
Symptom
Thermostat or RF receiver emits a clicking or buzzing noise frequently
Noisy Relay Operation / Electrical Buzz
Symptom
Thermostat shows frequent short heating cycles (boiler starts and stops every few minutes)
Short Cycling Due to Control Settings
Symptom
Thermostat shows room temperature that is clearly inaccurate (e.g., 5–10°C off compared to other thermometers)
Room Temperature Measurement Error
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
Thermostat shows E0 and cannot connect to the Saunier Duval cloud or mobile app
|
Cloud Service / Account Error | View Details |
| E1 |
Thermostat shows E1 and cannot connect to the home Wi‑Fi network
|
Wi‑Fi Connection Failure | View Details |
| E2 |
Thermostat shows E2 and mobile app cannot control it remotely, though Wi‑Fi appears connected
|
Server Communication / TLS Error | View Details |
| E3 |
Thermostat shows E3 and touch screen or buttons do not respond correctly
|
User Interface Hardware Error | View Details |
| E4 |
Thermostat shows E4 and battery icon flashes (for battery-powered models)
|
Low Battery Voltage | View Details |
| E5 |
Thermostat shows E5 and backlight flickers or unit restarts randomly
|
Power Supply Instability | View Details |
| E6 |
Thermostat shows E6 and cannot save new schedules or settings
|
Non-Volatile Memory Error | View Details |
| E7 |
Thermostat shows E7 and geolocation or weather-based functions are disabled
|
Location / GPS Service Error (App Integration) | View Details |
| E8 |
Thermostat shows E8 and cannot join the Saunier Duval account due to region mismatch
|
Region / Country Configuration Error | View Details |
| E9 |
Thermostat shows E9 and indicates pairing error with Saunier Duval internet gateway or RF bridge
|
Gateway Pairing Error | View Details |
| F0 |
Thermostat display shows F0 and boiler does not respond to temperature changes
|
Internal Sensor Calibration Error | View Details |
| F1 |
Thermostat shows F1 and cannot read room temperature (dashes or 0°C displayed)
|
Room Temperature Sensor Open Circuit | View Details |
| F2 |
Thermostat shows F2 and indicates an abnormally high room temperature or no temperature reading
|
Room Temperature Sensor Short Circuit | View Details |
| F3 |
Thermostat shows F3 and cannot control the boiler correctly; heating does not start or stops unexpectedly
|
Communication Failure with Boiler (eBus/OTBus) | View Details |
| F4 |
Thermostat shows F4 and cannot detect the wireless receiver or boiler gateway
|
Radio Link Failure to Wireless Receiver | View Details |
| F5 |
Thermostat shows F5 and cannot control domestic hot water temperature via the boiler
|
DHW Control Communication Error | View Details |
| F6 |
Thermostat shows F6 and schedules or setpoints are not applied to the boiler
|
Internal Clock / Timekeeping Error | View Details |
| F7 |
Thermostat shows F7 and cannot detect external temperature for weather-compensated control
|
Outdoor Sensor Communication Error | View Details |
| F8 |
Thermostat shows F8 and cannot control the boiler via OpenTherm mode
|
OpenTherm Protocol Error | View Details |
| F9 |
Thermostat shows F9 and heating demand is ignored by the boiler
|
Internal Relay / Output Failure | View Details |
| – |
Boiler runs continuously and overheats rooms even when thermostat is set low or off
|
Boiler Firing Without Thermostat Control | View Details |
| – |
Condensation or visible moisture inside thermostat housing
|
Moisture Ingress Affecting Electronics | View Details |
| – |
Room temperature overshoots the setpoint by several degrees before boiler turns off
|
Poor Temperature Regulation / Overshoot | View Details |
| – |
Thermostat backlight or display is very dim and hard to read
|
Display Illumination Degradation | View Details |
| – |
Thermostat calls for heat but boiler does not start (no error code on thermostat or boiler)
|
Control Signal Not Reaching Boiler | View Details |
| – |
Thermostat cannot be paired with the Saunier Duval app (QR code or serial not accepted)
|
Device Registration Failure | View Details |
| – |
Thermostat cannot control individual room zones or underfloor heating manifolds as expected
|
Zoning / Multi-Zone Control Misconfiguration | View Details |
| – |
Thermostat display is completely blank and unresponsive
|
No Power to Thermostat | View Details |
| – |
Thermostat does not detect open windows or does not activate energy-saving features when windows are opened
|
Open-Window Detection Not Working | View Details |
| – |
Thermostat does not follow programmed schedule; heating turns on/off at wrong times
|
Scheduling / Time Program Fault | View Details |
| – |
Thermostat frequently disconnects from Wi‑Fi and goes offline in the app
|
Intermittent Wi‑Fi Connectivity | View Details |
| – |
Thermostat loses all settings and pairing after a power cut
|
Loss of Non-Volatile Configuration | View Details |
| – |
Thermostat or RF receiver becomes very warm to the touch during normal operation
|
Overheating of Control Unit | View Details |
| – |
Thermostat or RF receiver emits a burning smell or visible smoke
|
Severe Electrical Failure / Overheating | View Details |
| – |
Thermostat or RF receiver emits a clicking or buzzing noise frequently
|
Noisy Relay Operation / Electrical Buzz | View Details |
| – |
Thermostat shows frequent short heating cycles (boiler starts and stops every few minutes)
|
Short Cycling Due to Control Settings | View Details |
| – |
Thermostat shows room temperature that is clearly inaccurate (e.g., 5–10°C off compared to other thermometers)
|
Room Temperature Measurement Error | View Details |
No matching codes found
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