Vaillant vSMART
Vaillant vSMART 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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App cannot connect to vSMART
The Vaillant app on a smartphone cannot connect to the vSMART system while on the same Wi‑Fi network; remote access may still work or vice versa.
Local API or Port Blocking
Boiler communication error
vSMART app shows 'Boiler communication error' and boiler may revert to basic operation or stop responding to vSMART commands.
Boiler Control Bus Error
Firmware update failed
vSMART app reports 'Firmware update failed' or the thermostat/gateway reboots repeatedly during an update.
Firmware Update Interruption
Frost protection active
vSMART indicates 'Frost protection' and maintains a low temperature even when higher setpoints are selected.
Frost Protection Mode Lock‑In
Gateway not found
During setup, the Vaillant app cannot find the vSMART internet gateway or reports 'Gateway not found'.
Initial Pairing Failure
Geofencing not active
Geofencing features in the vSMART app do not activate, and the app may show a warning that location services are disabled or unavailable.
Location Service Integration Failure
Internal error
vSMART thermostat or app briefly shows 'Internal error' or similar generic message and may reboot.
Controller Software Exception
Low battery
vSMART room thermostat displays a low battery icon or the app reports low battery status.
Thermostat Power Depletion
No connection to boiler
vSMART thermostat shows a message indicating no connection to the boiler; heating and/or hot water do not respond to setpoint changes.
eBUS Communication Failure
No heating demand
vSMART app shows no heating demand even though room temperature is below the setpoint; boiler remains off.
Demand Logic or Schedule Misconfiguration
No hot water demand
vSMART app shows no hot water demand or hot water remains cold despite schedule being active.
DHW Schedule or Priority Misconfiguration
Open window detected
vSMART app or thermostat indicates 'Open window detected' and temporarily reduces or stops heating in that room.
Rapid Temperature Drop Detection
Outdoor sensor error
vSMART system reports an 'Outdoor sensor error' or shows no outdoor temperature when one is configured.
Outdoor Temperature Sensor Circuit Fault
Room temperature reading unrealistic
vSMART shows a room temperature far from reality (e.g., 5°C or 40°C indoors) without a specific numeric error code.
Temperature Sensor Calibration or Failure
Room unit not detected
The vSMART gateway or boiler interface reports that the room thermostat unit is not detected or not paired.
Thermostat–Gateway Pairing Loss
Schedule conflict
vSMART app reports a 'Schedule conflict' or overlapping time periods that prevent proper operation.
Programming Conflict
Sensor error
vSMART thermostat or app displays a generic 'Sensor error' and cannot regulate temperature correctly.
Internal Temperature Sensor Fault
Time sync error
vSMART thermostat or app shows incorrect time or a 'Time sync' / 'Clock error' message, causing schedules to run at wrong times.
NTP Time Synchronization Failure
vSMART offline
Vaillant vSMART app shows thermostat offline and cannot control heating or hot water remotely.
Cloud Connectivity Loss
Zoning configuration error
vSMART app reports a zoning configuration error or zones do not behave as expected (wrong rooms heating).
Multi‑Zone Mapping Fault
Symptom
Boiler does not start at all for heating, but hot water may still work, even when vSMART calls for heat.
Heating Demand Path Failure
Symptom
Boiler runs continuously and overheats rooms even when vSMART setpoint is reached or heating is turned off in the app.
Stuck Heating Demand or Relay
Symptom
Condensation or visible moisture inside the thermostat housing or on the display.
Moisture Ingress
Symptom
Noticeable clicking or buzzing noises from the vSMART boiler interface or relay box when heating turns on or off.
Relay Operation Noise
Symptom
Radiators heat up when only hot water is scheduled, or hot water heats when only heating is scheduled.
Crossed Heating/DHW Control
Symptom
Some rooms are too hot while others remain cold, despite vSMART controlling the system.
Poor Heat Distribution / Balancing
Symptom
System makes frequent short boiler cycles (on/off every few minutes) even when there is a steady heat demand.
Short Cycling Due to Control or Sizing
Symptom
Thermostat buttons or touch interface are unresponsive or respond intermittently.
User Interface Hardware Fault
Symptom
Thermostat display completely dead, no backlight or response to button presses.
Thermostat Power Failure
Symptom
Thermostat frequently disconnects and reconnects to the vSMART gateway, causing intermittent control.
Unstable Wireless Link
Symptom
Thermostat or gateway feels unusually hot to the touch or is installed in a very warm location, causing erratic behavior.
Overheating of Control Electronics
Symptom
Unpleasant burning or electrical smell from the vSMART gateway or thermostat.
Overheating or Electrical Short
Symptom
vSMART app shows inconsistent or delayed temperature updates compared to the thermostat display.
Cloud Sync Latency
Symptom
vSMART loses all schedules and settings after a power cut or reboot.
Non‑Volatile Memory Failure or Cloud Sync Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| App cannot connect to vSMART |
The Vaillant app on a smartphone cannot connect to the vSMART system while on the same Wi‑Fi network; remote access may still work or vice versa.
|
Local API or Port Blocking | View Details |
| Boiler communication error |
vSMART app shows 'Boiler communication error' and boiler may revert to basic operation or stop responding to vSMART commands.
|
Boiler Control Bus Error | View Details |
| Firmware update failed |
vSMART app reports 'Firmware update failed' or the thermostat/gateway reboots repeatedly during an update.
|
Firmware Update Interruption | View Details |
| Frost protection active |
vSMART indicates 'Frost protection' and maintains a low temperature even when higher setpoints are selected.
|
Frost Protection Mode Lock‑In | View Details |
| Gateway not found |
During setup, the Vaillant app cannot find the vSMART internet gateway or reports 'Gateway not found'.
|
Initial Pairing Failure | View Details |
| Geofencing not active |
Geofencing features in the vSMART app do not activate, and the app may show a warning that location services are disabled or unavailable.
|
Location Service Integration Failure | View Details |
| Internal error |
vSMART thermostat or app briefly shows 'Internal error' or similar generic message and may reboot.
|
Controller Software Exception | View Details |
| Low battery |
vSMART room thermostat displays a low battery icon or the app reports low battery status.
|
Thermostat Power Depletion | View Details |
| No connection to boiler |
vSMART thermostat shows a message indicating no connection to the boiler; heating and/or hot water do not respond to setpoint changes.
|
eBUS Communication Failure | View Details |
| No heating demand |
vSMART app shows no heating demand even though room temperature is below the setpoint; boiler remains off.
|
Demand Logic or Schedule Misconfiguration | View Details |
| No hot water demand |
vSMART app shows no hot water demand or hot water remains cold despite schedule being active.
|
DHW Schedule or Priority Misconfiguration | View Details |
| Open window detected |
vSMART app or thermostat indicates 'Open window detected' and temporarily reduces or stops heating in that room.
|
Rapid Temperature Drop Detection | View Details |
| Outdoor sensor error |
vSMART system reports an 'Outdoor sensor error' or shows no outdoor temperature when one is configured.
|
Outdoor Temperature Sensor Circuit Fault | View Details |
| Room temperature reading unrealistic |
vSMART shows a room temperature far from reality (e.g., 5°C or 40°C indoors) without a specific numeric error code.
|
Temperature Sensor Calibration or Failure | View Details |
| Room unit not detected |
The vSMART gateway or boiler interface reports that the room thermostat unit is not detected or not paired.
|
Thermostat–Gateway Pairing Loss | View Details |
| Schedule conflict |
vSMART app reports a 'Schedule conflict' or overlapping time periods that prevent proper operation.
|
Programming Conflict | View Details |
| Sensor error |
vSMART thermostat or app displays a generic 'Sensor error' and cannot regulate temperature correctly.
|
Internal Temperature Sensor Fault | View Details |
| Time sync error |
vSMART thermostat or app shows incorrect time or a 'Time sync' / 'Clock error' message, causing schedules to run at wrong times.
|
NTP Time Synchronization Failure | View Details |
| vSMART offline |
Vaillant vSMART app shows thermostat offline and cannot control heating or hot water remotely.
|
Cloud Connectivity Loss | View Details |
| Zoning configuration error |
vSMART app reports a zoning configuration error or zones do not behave as expected (wrong rooms heating).
|
Multi‑Zone Mapping Fault | View Details |
| – |
Boiler does not start at all for heating, but hot water may still work, even when vSMART calls for heat.
|
Heating Demand Path Failure | View Details |
| – |
Boiler runs continuously and overheats rooms even when vSMART setpoint is reached or heating is turned off in the app.
|
Stuck Heating Demand or Relay | View Details |
| – |
Condensation or visible moisture inside the thermostat housing or on the display.
|
Moisture Ingress | View Details |
| – |
Noticeable clicking or buzzing noises from the vSMART boiler interface or relay box when heating turns on or off.
|
Relay Operation Noise | View Details |
| – |
Radiators heat up when only hot water is scheduled, or hot water heats when only heating is scheduled.
|
Crossed Heating/DHW Control | View Details |
| – |
Some rooms are too hot while others remain cold, despite vSMART controlling the system.
|
Poor Heat Distribution / Balancing | View Details |
| – |
System makes frequent short boiler cycles (on/off every few minutes) even when there is a steady heat demand.
|
Short Cycling Due to Control or Sizing | View Details |
| – |
Thermostat buttons or touch interface are unresponsive or respond intermittently.
|
User Interface Hardware Fault | View Details |
| – |
Thermostat display completely dead, no backlight or response to button presses.
|
Thermostat Power Failure | View Details |
| – |
Thermostat frequently disconnects and reconnects to the vSMART gateway, causing intermittent control.
|
Unstable Wireless Link | View Details |
| – |
Thermostat or gateway feels unusually hot to the touch or is installed in a very warm location, causing erratic behavior.
|
Overheating of Control Electronics | View Details |
| – |
Unpleasant burning or electrical smell from the vSMART gateway or thermostat.
|
Overheating or Electrical Short | View Details |
| – |
vSMART app shows inconsistent or delayed temperature updates compared to the thermostat display.
|
Cloud Sync Latency | View Details |
| – |
vSMART loses all schedules and settings after a power cut or reboot.
|
Non‑Volatile Memory Failure or Cloud Sync Issue | View Details |
No matching codes found
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